half-Jewish

"Who is a Jew?" ( he, מיהו יהודי ) is a basic question about Jewish identity and considerations of Jewish self-identification. The question pertains to ideas about Jewish personhood, which have cultural, ethnic, religious, political, genealogical, and personal dimensions. Orthodox Judaism and Conservative Judaism follow Jewish law (Halakha), deeming people to be Jewish if their mothers are Jewish or if they underwent a halakhic conversion to Judaism#Halakhic considerations, conversion. Reform Judaism and Reconstructionist Judaism accept both matrilineal and patrilineal descent as well as conversion. Karaite Judaism predominantly follows patrilineal descent as well as conversion.

Jewish identity is also commonly defined through ethnicity. Opinion polls have suggested that the majority of Jews see being Jewish as predominantly a matter of ancestry and culture, rather than religion.

is a Jew?

The term "Jew" lends itself to several definitions beyond simply denoting one who practices Judaism. The historical Israelites and/or Hebrews, who promulgated Judaism, were not simply a homogeneous assemblage united by a common ideology, that being the Jewish religion; they constituted an ethnoreligious group from whom a majority of modern Jews directly descend, Israelite origins and kingdom: "The first act in the long drama of Jewish history is the age of the Israelites""The people of the Kingdom of Israel and the ethnic and religious group known as the Jewish people that descended from them have been subjected to a number of forced migrations in their history" and therefore an ethnic form of Jewish identity exists alongside the religious form of Jewish identity. As such, the concepts of Jewish ethnicity, nationhood, and religion are strongly interrelated, "Historically, the religious and ethnic dimensions of Jewish identity have been closely interwoven. In fact, so closely bound are they, that the traditional Jewish lexicon hardly distinguishes between the two concepts. Jewish religious practice, by definition, was observed exclusively by the Jewish people, and notions of Jewish peoplehood, nation, and community were suffused with faith in the Jewish God, the practice of Jewish (religious) law and the study of ancient religious texts" "This identification in the Jewish attitude between the ethnic group and religious identity is so close that the reception into this religion of members not belonging to its ethnic group has become impossible." however, through conversion, it is possible for one who has no historical connection to the historical Jewish population to become a Jew, in that sense.

In essence, the word "Jew" can be defined as a conglomerate of several different, albeit closely related, ideas:

* A Jew is one who practices the Jewish religion, Judaism. This includes both converts and those who have been members of the Jewish religion since birth.
* A Jew is one who is a descendant of the ancient Israelite ethnic group, and therefore is a member of the Jewish ''people''. This includes those who may not be observantly religious, or may be irreligious altogether, and claim an overtly cultural connection. "A person born Jewish who refutes Judaism may continue to assert a Jewish identity, and if he or she does not convert to another religion, even religious Jews will recognize the person as a Jew"
* A Jew is one who, regardless of current religious identity, is directly descended from a Jewish ancestor. Traditionally, this has only applied to matrilineal ancestry, however, some Jewish groups also recognize Jewishness by way of patrilineal descent.

Traditional interpretation and variations

The definition of who is a Jew varies according to whether it is being considered by Jews on the basis of religious law and tradition or self-identification, or by non-Jews for other reasons, sometimes for prejudicial purposes. Because Jewish identity can include characteristics of an ethnicity,
Ethnic minorities in English law
Google Books. Retrieved 2010-12-23.
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* a religion, or peoplehood, the definition depends on either traditional or newer interpretations of Jewish law and custom.

Israel's Law of Return stipulates that a Jew is someone with a Jewish mother or someone who has converted to Judaism and is not a member of another religion. The Israeli Chief Rabbinate requires documents proving the Jewishness of one’s mother, grandmother, great-grandmother and great-great-grandmother when applying for marriage. The Office of the Chief Rabbi (OCR) has underlined the basic principle that a child is not recognised by the OCR and other bodies as Jewish unless their mother is Jewish, or they underwent a conversion recognized by the body.

According to the simplest definition used by most Jews for self-identification, a person is a Jew by birth or becomes one through religious conversion. However, there are differences in interpretations when it comes to non- Orthodox Jewish denominations in the application of this definition, including

* Should a person with only a Jewish father be considered Jewish?
* Which conversion processes should be considered valid?
* Can one remain a Jew after converting to another religion?
* How does being unaware of having Jewish parents affect one's Jewish status?
* How is Jewish identity determined in different countries throughout the Jewish Diaspora?
* How is the claim to Israeli citizenship adjudicated in the context of the Basic Laws of Israel?

Tannaitic Judaism

According to the Mishnah, the first written source for halakha, the status of the offspring of mixed marriages was determined matrilineally.

According to historian Shaye J. D. Cohen, in the Bible, the status of the offspring of mixed marriages was determined patrilineally. He brings two likely explanations for the change in Mishnaic times: first, the Mishnah may have been applying the same logic to mixed marriages as it had applied to other mixtures (''kilayim''). Thus, a mixed marriage is forbidden as is the union of a horse and a donkey, and in both unions the offspring are judged matrilineally. Second, the Tannaim may have been influenced by Roman law, which dictated that when a parent could not contract a legal marriage, offspring would follow the mother.

Contemporary Judaism

All Jewish religious movements agree that a person may be a Jew either by birth or through conversion. According to ''halakha,'' a Jew by birth must be born to a Jewish mother. ''Halakha'' states that the acceptance of the principles and practices of Judaism does not make a person a Jew. However, those born Jewish do not lose that status because they cease to be observant Jews, even if they adopt the practices of another religion.

Reform and Reconstructionist Judaism, as movements which reject the concept of ''halakha'', often accept a child as Jewish when only the father is Jewish, provided that the child chooses to identify as Jewish. As conversion processes differ, those performed by more liberal denominations are not accepted by more orthodox denominations.

Jewish by birth

According to ''halakha'', to determine a person's Jewish status (Hebrew: ) one needs to consider the status of both parents. If both parents are Jewish, their child will also be considered Jewish, and the child takes the status of the father (e.g., as a kohen). If either parent is subject to a genealogical disability (e.g., is a mamzer) then the child is also subject to that disability. If one of the parents is not Jewish, the rule is that the child takes the status of the mother ( Kiddushin 68b, Shulchan Aruch, EH 4:19).
The ruling is derived from various sources including , , . Accordingly, if the mother is Jewish, so is her child, and if she is not Jewish, neither is her child considered Jewish. In Orthodox Judaism the child of a non-Jewish mother can be considered Jewish only by a process of conversion to Judaism. The child is also freed from any disabilities and special status to which the father may have been subject (e.g., being a mamzer or kohen) under Jewish law.

The Orthodox and Conservative branches of Judaism maintain that the halakhic rules (i.e. matrilineal descent) are valid and binding. Reform and Liberal Judaism do not accept the halakhic rules as binding, and most branches accept a child of one Jewish parent, whether father or mother, as Jewish if the parents raise the child as a Jew and foster a Jewish identity in the child, noting that "in the Bible the line always followed the father, including the cases of Joseph and Moses, who married into non-Israelite priestly families."''Patrilineal Descent'', Jewish Virtual Library
. Retrieved September 2, 2008. (However, according to the oral tradition of Orthodox Judaism, the spouses of both Joseph and Moses converted to Judaism prior to marrying them.) The Reform movement's standard states that "for those beyond childhood claiming Jewish identity, other public acts or declarations may be added or substituted after consultation with their rabbi". Advocates of patrilineal descent point to and . This policy is commonly known as patrilineal descent, though "bilineal" would be more accurate.

Patrilineal descent

In 1983, the Reform Central Conference of American Rabbis passed the Resolution on Patrilineal Descent, declaring that "the child of one Jewish parent is under the presumption of Jewish descent. This presumption of the status of the offspring of any mixed marriage is to be established through appropriate and timely public and formal acts of identification with the Jewish faith and people ... Depending on circumstances, mitzvot leading toward a positive and exclusive Jewish identity will include entry into the covenant, acquisition of a Hebrew name, Torah study, Bar/Bat Mitzvah, and Kabbalat Torah (Confirmation). For those beyond childhood claiming Jewish identity, other public acts or declarations may be added or substituted after consultation with their rabbi."

Rabbi Mark Washofsky summarizes the 1983 CCAR resolution and subsequent interpretations in Reform responsa literature as follows:
* "The resolution is advisory rather than halachic in the traditional sense. It does not establish a new definition of Jewish identity, for its preamble states expressly that it means to be operative only for Reform Jews in North America, not for all Jews everywhere."
* "Jewish descent may be from either parent ...The Reform Movement presumes the child of ''one'' Jewish parent, either mother or father, as Jewish. In fact, the 1983 resolution is in one significant respect more stringent than the traditional definition of Jewish status. The child of a Jewish mother and gentile father, whom halachah regards as clearly Jewish, enjoys but a ''presumption'' of Jewish status that must be "established" by "appropriate and timely public and formal acts of identification."
* "Biology remains a crucial factor. In the determination of Jewish identity ... the child of ''two gentile'' parents is, as before, definitely a non-Jew and must undergo a formal conversion in order to become a Jew."
* "Both descent and behavior are crucial in determining Jewish status under the resolution. The Jewish status of a child of an intermarriage cannot be determined "automatically" either by biology or behavior. Both elements—descent from one Jewish parent ''and'' the performance of mitzvot that lead to a "positive and exclusive Jewish identity—must be present, and they must be present during childhood."
* "The resolution applies only to children raised exclusively as Jews ... A child raised simultaneously in Judaism and another religious tradition does not develop a "positive and exclusive" Jewish identity; therefore the presumption of Jewish status is disproved, and the resolution does not apply to that child. He or she will require conversion prior to celebrating becoming bar or bat mitzvah in the synagogue."

Waiving the need for formal conversion for anyone with at least one Jewish parent who has made affirmative acts of Jewish identity was a departure from the traditional position requiring formal conversion to Judaism for children without a Jewish mother.

The CCAR's 1983 resolution has had a mixed reception in Reform Jewish communities outside the United States. Most notably, the Israel Movement for Progressive Judaism has rejected patrilineal descent and requires formal conversion for anyone not born of a Jewish mother.

Karaite Judaism believes that Jewish identity can only be transmitted by patrilineal descent, on the grounds that all descent in the Torah went according to the male line, basing this idea "on the fact that, in the Bible, tribes are given male names and that biblical characters are always referenced by their fathers' names.p.154, Levinson, David (Ed.), ''Encyclopedia of World Cultures Vol 9 : Africa and the Middle East'', G. K. Hall & Co., Boston, 1995 However, a minority of modern Karaites believe that Jewish identity requires that both parents be Jewish, and not only the father.

The divergence of views has become an issue because Orthodox and Conservative communities do not recognize a person as Jewish if only their father is Jewish. For the person to be accepted as Jewish by an Orthodox or Conservative community (for example, on an occasion of their bar or bat mitzvah or marriage), they require a formal conversion (in accordance with halakhic standards). Orthodox Judaism has a predominant position in Israel. Although Orthodox and Conservative Judaism do not recognize Jewishness through patrilineal descent, "it should also be noted, however, that in the case of a child born to a Jewish father but to a non-Jewish mother, most Orthodox rabbis will relax the stringent demands normally made of would-be converts", and the Rabbinical Assembly of the Conservative movement "agreed that 'sincere Jews by choice' should be warmly welcomed into the community".

Converts to Judaism

All mainstream forms of Judaism today are open to sincere converts, with most subgroups having a specific process for accepting converts. Not all conversions are recognised by all varieties of Judaism.

In Rabbinic Judaism, the laws of conversion are based on the classical sources of Jewish law, especially discussions in the Talmud, and the law as codified in the Shulkhan Arukh. This corpus of traditional Jewish law (halakha) is regarded as authoritative by the Orthodox as quoted in and Conservative movements. The traditional halakhic requirements for conversion are instruction in the commandments, circumcision (if male), and immersion in an acceptable body of water before valid witnesses, and acceptance of the commandments before a rabbinical court. If a male is already circumcised, a drop of blood is drawn from the penis.

Orthodox authorities require that conversions be performed in accord with traditional Jewish law and recognise only those conversions in which a convert accepts and undertakes to observe Jewish law as interpreted by Orthodox rabbis. Because rabbis in the other movements do not require that converts make this commitment, Orthodox authorities do not generally accept as valid conversions performed outside the Orthodox community.

Conservative authorities likewise require that conversions be conducted according to traditional Jewish law. Conducting a conversion absent the traditional requirements of immersion in a ritual bath and circumcision for males is a violation of a Standard of the Rabbinical Assembly and grounds for expulsion. Conservative authorities generally recognize any conversion done in accord with the requirements of Jewish law, even if done outside the Conservative movement. Accordingly, Conservative rabbis may accept the validity of some conversions from other non-Orthodox movements.

The Union for Reform Judaism states that "people considering conversion are expected to study Jewish theology, rituals, history, culture and customs, and to begin incorporating Jewish practices into their lives. The length and format of the course of study will vary from rabbi to rabbi and community to community, though most now require a course in basic Judaism and individual study with a rabbi, as well as attendance at services and participation in home practice and synagogue life." Its Central Conference of American Rabbis recommends that three rabbis be present for the conversion ceremony. The Rabbinical Court of the Israel Movement for Progressive Judaism requires an average of a year of study to become conversant in Jewish life and tradition. Following this, converts are required to immerse in a ritual bath, be circumcised if male, and accept the commandments before the rabbinical court.

Although an infant conversion might be accepted in some circumstances (such as in the case of adopted children or children whose parents convert), children who convert would typically be asked if they want to remain Jewish after reaching religious adulthood – which is 12 years of age for a girl and 13 for a boy, as required by Jewish law.

Karaite Judaism does not accept the oral legal traditions of Rabbinic Judaism. It has different requirements for conversion and refrained from accepting any converts until recently. Traditionally non-proselytizing, on August 1, 2007, the Karaites reportedly converted their first new members in 500 years. At a ceremony in their Northern California synagogue, ten adults and four minors swore fealty to Judaism after completing a year of study. This conversion came 15 years after the Karaite Council of Sages reversed its centuries-old ban on accepting converts.

Syrian Jewish communities do not normally carry out conversions, particularly where the conversion is suspected of being for the sake of marriage. Nor do they accept such converts from other communities, or the children of mixed marriages or marriages involving such converts.

Jews who have practiced another religion

In general, Orthodox Judaism considers individuals born of Jewish mothers to be Jewish, even if they convert to or are raised in another religion. Reform Judaism views Jews who convert to or are raised in another religion as non-Jews. For example "... anyone who claims that Jesus is their savior is no longer a Jew ..." ontemporary American Reform Responsa, #68

Historically, a Jew who has been declared to be a heretic ( he, מין, min, links=no) or Christian ( he, נוצרי, notzri, links=no, meaning "Nazarene") may have had a '' cherem'' (similar to excommunication) placed on him or her; but the practice of communal and religious exclusion does not affect their status of Jewish birth. Judaism also views as Jewish those who involuntarily convert from Judaism to another religion (Hebrew: ''anusim,'' אנוסים, meaning "forced ones"), and their matrilineal descendants are likewise considered to be Jewish.

Judaism has a category for those who are Jewish but who do not practice or who do not accept the tenets of Judaism, whether or not they have converted to another religion. The traditional view regarding these individuals, known as Meshumadim ( he, משומדים, links=no), is that they are Jewish; however, there is much debate in the rabbinic literature regarding their status vis-a-vis the application of Jewish law and their participation in Jewish ritual, but not to their status as Jews.

A Jew who leaves Judaism is free to return to the religion at any time. In general, no formal ceremony or declaration is required to return to Jewish practices. All movements of Judaism welcome the return to Judaism of those who have left, or been raised in another religion. When returning to Judaism, these individuals would be expected to abandon their previous practices and adopt Jewish customs.

The same rules in principle apply to the matrilineal descendants of such persons, though some rabbinical authorities may require stricter proof of Jewish descent than others. Whether such persons are required to undergo a full formal conversion depends on the community and their individual circumstances. For example, a male who has had a brit milah, who has a general understanding of Judaism, but who has been raised in a secular home might not be required to undergo ritual conversion. However, a male who has not had a brit milah, a male or female who has converted to or been brought up in another religion, or an individual raised in a completely secular home without any Jewish education, in most communities, may be required to undergo a full ritual conversion. For full participation in the community (for example, to marry with the participation of a rabbi), they may be required to display sincerity, such as a declaration of commitment to Judaism.

Another example of the issues involved is the case of converts to Judaism who cease to practice Judaism (whether or not they still regard themselves as Jewish), do not accept or follow halakha, or now adhere to another religion. Technically, such a person remains Jewish, like all Jews, provided that the original conversion is valid. However, in some recent cases, Haredi rabbinical authorities, as well as the current Religious Zionist Israeli Chief Rabbinate, have taken the view that a given convert's lapse from Orthodox Jewish observance is evidence that he or she cannot, even at the time of the conversion, have had the full intention to observe the commandments and that the conversion must therefore have been invalid.

A valid Jewish court of sufficient stature has the ability to revoke a person's or a group's status as Jews. This was done for the lost Ten Tribes of Israel and the Samaritans.

Religious definitions

Halakhic perspective

According to the traditional Rabbinic view, which is maintained by all branches of Orthodox Judaism and Conservative Judaism, and some branches of Reform Judaism, only ''halakha'' can define who is or is not a Jew when a question of Jewish identity, lineage, or parentage arises about any person seeking to define themselves or claim that they are Jewish.

As a result, mere ''belief'' in the principles of Judaism does ''not'' make one a Jew. Similarly, non-adherence by a Jew to the 613 Mitzvot, or even formal conversion to another religion, does not make one lose one's Jewish status. Thus, the immediate descendants of all female Jews (even apostates) are still considered to be Jews, as are those of all their female descendants. Even those descendants who are not aware they are Jews or practice a religion other than Judaism, are defined by this perspective as Jews, as long as they come from an unbroken female line of descent. As a corollary, the children of a Jewish father and a non-Jewish mother are not considered to be Jews by Halakha unless they formally convert according to Halakha, even if raised fully observant in the Mitzvot.

Those not born to a Jewish mother may become accepted as Jews by the Orthodox and Conservative communities through a formal process of conversion to Judaism in order to become "righteous converts" ('— he, גרי צדק). In addition, Halakha requires that the new convert commit himself to the observance of its tenets; this is called ' ( he, קבלת עול מצוות), "Acceptance of the Yoke of the Commandments". ' ( he, קבלת מצוות) is used by Reform Judaism in accordance with reform responsa and Halakhah.

Both Haredi Judaism and Modern Orthodox Judaism accept a similar set of rules regarding Jewish status based on classical rabbinic Judaism, including both matrilineal descent and requirements that conversions be performed by Orthodox rabbis and that converts promise to strictly observe elements of traditional Judaism such as Shabbat and Niddah. However, their application of these rules have been different, and the difference has been increasing in recent years. Modern Orthodox authorities have been more inclined to rule in favor of Jewish status and to accept non-Orthodox Jews' word in doubtful cases involving people claiming to be Jews, while Haredi authorities have in recent years tended to presume non-Jewish status and require more stringent rules and standards of evidence in order for Jewish status to be proven, and have tended to distrust the evidence of Jews who are not personally Orthodox. Haredi rabbis have tended to look at a convert's current personal observance and to regard deficiencies or lack of Orthodoxy in current observance as evidence that the convert never intended to validly convert. In addition, the contemporary situation is further complicated by the fact that some Haredi rabbis no longer regard some Modern Orthodox rabbis as reliable.

Karaite Judaism

Karaite Judaism relies on the Tanakh to indicate that Jewishness is passed down through the paternal line, not the maternal line as is maintained by Orthodox Judaism (though a minority holds that both parents need to be Jewish). Karaite Jews are eligible for Aliyah under the Law of Return. The eligibility of converts to Judaism through the Karaite movement to make Aliyah under the Law of Return has not yet been addressed in Israeli courts.

Several verses in the Bible mentioning about laws of family inheritance depending on the paternal lineage of the tribe:

Reform Judaism

Reform Judaism recognizes a child as being Jewish if either parent is Jewish and the child is being raised Jewish. Voices within the Reform movement say that the law, which changed to matriarchal around 2,000 years ago (originally in the Torah the offspring was determined by patriarchal descent) and was based on the tragic circumstances the Jewish people were facing, was once helpful but is no longer relevant.

Modern Progressive Jewish denominations have a conversion process based on their principles. In the US, an official Reform resolution in 1893 abolished circumcision as a requirement for converts, and Reform does not require converts to have ''tevilah,'' ritual immersion. A "prospective convert declares, orally and in writing, in the presence of a rabbi and no less than two lay leaders of the congregation and community, acceptance of the Jewish religion and the intention to live in accordance with its ''mitzvot''".

Controversies

The controversy in determining "who is a Jew" concerns four basic issues:

One issue arises because North American Reform and UK Liberal movements have changed some of the halakhic requirements for Jewish identity in two ways:

Secondly, Orthodox Judaism asserts that non-Orthodox rabbis are not qualified to form a ''beit din.'' This has led to non-Orthodox conversions generally being unaccepted in Orthodox communities. Since Orthodox Judaism maintains the traditional standards for conversion – in which the commitment to observe halakha is required – non-Orthodox conversions are generally not accepted in Orthodox communities because the non-Orthodox movements perform conversions in which the new convert does not undertake to observe halakha as understood by Orthodox Judaism.

A third controversy concerns persons (whether born Jews or converts to Judaism) who have converted to another religion. The traditional view is such persons remain Jewish. Reform Judaism regards such people as apostates, and states regarding Messianic Jews: Messianic Jews' claim that they are Jews, but we must asked ourselves whether we identify them as Jews. We can not do so as they consider Jesus of Nazareth as the Messiah who has fulfilled the Messianic promises. In this way, they have clearly placed themselves within Christianity. They may be somewhat different from other Christians as they follow various Jewish rites and ceremonials, but that does not make them Jews." Regardless, such people do not count as Jewish for the purposes of the Israeli citizenship laws.

A fourth controversy stems from the manner in which the Chief Rabbinate of Israel has been handling marriage and conversion decisions in recent years. Conversions and marriages within Israel are legally controlled by the Orthodox Israeli Chief Rabbinate; therefore, a person not proven to be a Jew to the Rabbinate's satisfaction is not legally permitted to marry a Jew in Israel today. Although the Rabbinate has always refused to accept non-Orthodox conversions, until recent years it was more willing to accept the Jewish parentage of applicants based on personal testimony, and the validity of conversions based on the testimony of Orthodox Rabbis. However, in recent years the rabbinate, whose rabbis historically had a more Modern Orthodox orientation, has increasingly been filled by the more stringent Haredi camp. It has increasingly been inclined to presume that applicants are not Jewish until proven otherwise, and require more stringent standards of proof than in the past. It has implemented a policy of refusing to accept the testimony of non-Orthodox Jews in matters of Jewish status, on grounds that such testimony is not reliable. It also has been increasingly skeptical of the reliability of Orthodox rabbis ordained by institutions not subject to its accreditation, particularly in matters of conversion. Accordingly, non-Orthodox Jews born to Jewish parents, and some Jews converted by Orthodox rabbis, have been increasingly unable to prove their Jewishness to the Rabbinate's satisfaction, because they are unable to find an Orthodox rabbi who is both acceptable to the Rabbinate, and familiar with and willing to vouch for the Jewishness of their maternal lineage or the validity of their conversion.

There have been several attempts to convene representatives of the three major movements to formulate a practical solution to this issue. To date, these have failed, though all parties concede the importance of the issue is greater than any sense of rivalry among them.

Ethnic definitions

''Ethnic Jew'' is a term generally used to describe a person of Jewish parentage and background who does not necessarily actively practice Judaism, but still identifies with Judaism or other Jews culturally or fraternally, or both. The term ''ethnic Jew'' does not specifically exclude practicing Jews, but they are usually simply referred to as "Jews" without the qualifying adjective "ethnic".

The term can refer to people of diverse beliefs and backgrounds because genealogy largely defines who is "Jewish". "Ethnic Jew" is sometimes used to distinguish non-practicing from practicing (religious) Jews. Other terms include ''non-observant Jew'', ''non-religious Jew'', ''non-practicing Jew'', and ''secular Jew''.

The term may also refer to Jews who do not practice the religion of Judaism. Typically, ethnic Jews are cognizant of their Jewish background and may feel strong cultural (even if not religious) ties to Jewish traditions and to the Jewish people or nation. Like people of any other ethnicity, non-religious ethnic Jews often assimilate into a surrounding non-Jewish culture, but, especially in areas where there is a strong local Jewish culture, they may remain largely part of that culture instead.

"Ethnic Jews" include atheists, agnostics, non-denominational deists, Jews with only casual connections to Jewish denominations or converts to other religions, such as Christianity, Buddhism, or Islam. Religious Jews of all denominations sometimes engage in outreach to non-religious Jews. In the case of some Hasidic denominations (e.g. Chabad-Lubavitch), this outreach extends to actively proselytizing more secular Jews.

Public opinion

The 2013 Pew Research study of American Jews found that 62% thought that being Jewish was mainly a matter of ancestry and culture, while 15% thought that it was mainly a matter of religion. Of those who stated themselves to be Jews by religion, 55% thought that being Jewish was mainly a matter of ancestry and culture, while two-thirds thought that it was not necessary to believe in God to be Jewish.

Historical European definitions

During the Middle Ages there was no need to ask the question "who is a Jew?", because the difference between the Jewish and the non-Jewish community was clear to both sides.Nicholas de Lange: ''Atlas of the Jewish world'', p. 79. Equinox, 1991.Gitelman, Zvi: ''Jewish Identities in Postcommunist Russia and Ukraine'', p. 62. Cambridge University Press, 2012. For example, a person born to a Jewish family was Jewish, marriages between Jews and non-Jews were not allowed, and the only way to leave the Jewish identity was through not only leaving the religion, but also cutting all ties to the Jewish community, including family and friends. To Medieval Jews the most essential difference between them and others was not about faith but about the peoplehood, to which their religious community was tied into, and they called themselves "Israel".

As the emancipation for Jews in Europe became relevant, the ideology of nationalism started rising and in parts of the Western Europe religion became more clearly separated from ethnicity, the question of what kind of a group the Jews were, religious, cultural, racial, national or something else, became discussed more. Due to emancipation, Jews were expected to assimilate into European nations. Religious difference was tolerated better than ethnic,Gitelman, Zvi (ed.): ''Religion or Ethnicity? Jewish Identities in Evolution''. Rutgers University Press, 2009. and Jews were now sometimes defined just as a religious group, e.g. Jews in Germany were defined as Germans who practice "Mosaic faith". Jews themselves were usually not happy with this definition. Yet, as seeking for equal civil rights and to prove that Jews can be a part of Western civilizations as well, some Central European Jews started highlighting their identity more as a religious group, with some rejecting ethnic definitions of Jewishness completely and some consciously getting rid of their "oriental" habits. Many Jews however, especially in Eastern Europe, criticized Western Jews for losing their Jewishness. Still, simultaneously, the concept of "Semitic race", which included the Jews, was coined. This also lead to pseudoscientific ideas of Jews being racially inferior to "Aryans".Harviainen, Tapani & Illman, Karl-Johan (ed.): ''Juutalainen kulttuuri'', p. 33. Keuruu: Otava, 2003. Later the Holocaust caused some more Jews to avoid attaching ethnic or racial elements to being Jewish. In the former Soviet Union, "Jewish" was a nationality by law, as with other nationalities such as Russians, Ukrainians, Georgians and others, and Soviet Jews themselves had a strong sense of ethnic Jewishness ("''Yiddishkeit''") which would have separated them from surrounding ethnic groups. There were certain restrictions on their civil liberties in the early years of the Soviet Union.

DNA

The modern genealogical DNA test of ethnicity is a non-religious definition of 'who is a Jew?' as increasing numbers of persons discover their biological and cultural origins outside the traditional religious setting. There has been controversy about the use of DNA tests in Israeli rabbinical courts as a test of Jewishness.

"Half-Jewish"

In the United States and Europe, because of intermarriage, the population of "half-Jews" is beginning to rival that of Jews with two Jewish parents. Self-identified "half-Jews" consider the term a familial category, which reflects multiple heritages and possible Jewish cultural or spiritual practices.Daniel Klein and Freke Vuijst, ''The Half-Jewish Book: A Celebration'', New York: Villard Books, 2000. Other similar terms that have been used include: "part-Jewish" and "partial-Jews". The term "Gershom", "Gershomi" or "Beta Gershom" has also been seldom used as an alternative to "half-Jewish" and "part-Jewish" in connection with descendants of intermarriage, Gershom being the biblical son of Moses and his Midianite wife Zipporah. The term typically has no religious meaning, as terms like Jewish Christian do, but rather describes ethnic Jewry.

Other non-religious definitions

The Society for Humanistic Judaism defines a Jew as "someone who identifies with the history, culture and fate of the Jewish people". In their view it is, therefore, possible for a non-religious individual to adopt Judaism and join a Humanistic Jewish community, and for the Society for Humanistic Judaism to adopt the person wanting to be part of the Humanistic Jewish family. As Israeli author Amos Oz puts it, "a Jew is anyone who chooses or is compelled to share a common fate with other Jews." Oz summed up his position more succinctly in a monologue published in '' Tikkun'', saying "Who is a Jew? Everyone who is mad enough to call himself or herself a Jew is a Jew.". From a similar perspective it is possible for a person born and raised as a Jew to leave Judaism and no longer be a Jew: famous historical examples are Heinrich Heine, Benjamin Disraeli, Gustav Mahler, Georg Brandes.

Legal structure in Israel

Israeli constitutional documents have not defined "who is a Jew" although the decision whether someone is Jewish or not has important legal, social and financial ramifications. This lack of definition has given rise to legal controversy in Israel and there have been many court cases in Israel that have addressed the question.Navot, Suzi, ''Constitutional law of Israel'', p.189Uzi Rebhun, Chaim Isaac Waxman, ''Jews in Israel: contemporary social and cultural patterns'', pp.296–297

Judaism test

, anyone who immigrated to Israel after 1990 and wishes to marry or divorce via the Jewish tradition within the state limits must go through a "Judaism test" at an Orthodox Rabbinical court. In this test, a person would need to prove their claim to be Jewish to an investigator beyond a reasonable doubt. They would need to present original documentation of their matriline up to their great-grandmother (4 generations), or in the case of Ethiopian Jews, 7 generations back. In addition, they should provide government documents with nationality/religion shown as Jewish (e.g., birth/death certificates, marriage documents, etc.).

In the case of people whose original documents have been lost or never existed, it may take considerable effort to prove they are Jewish.
The court rulings are not final, and any clerk has the power to question them even 20 years later, changing one's citizenship status to "on hold", and putting them in jeopardy of deportation.

The two biggest communities affected by these documentation issues are:
* Immigrants from the former Soviet Union