In the 19th century there was intellectual and spiritual awakening in Constantinople. This awakening and enlightenment pushed the reformists to study the Bible. Under the patronage of the Armenian Patriarchate, a school was opened, headed by Krikor Peshdimaljian, one of the leading intellectuals of the time. The principal aim of this school was to train qualified clergy for the Armenian Apostolic Church.
The result of this awakening was the formation of a society called the "Pietistical Union". The members held meetings for the study of the Bible. During these meetings and Bible studies, questions were raised regarding the practices and traditions of the church, which to them seemed to conflict with biblical truths.
These reformists faced strong retaliation from the Armenian Patriarchate of Constantinople. Eventually, after Patriarch Matteos Chouhajian excommunicated the reformists, they were forced to organize themselves into a separate religious community, the Protestant Millet. This separation led to the formation of the Armenian Evangelical Church in 1846.
Today, there are approximately 100 Armenian Evangelical churches in the following countries: Argentina, Armenia, Australia, Belgium, Brazil, Bulgaria, Canada, Cyprus, Egypt, England, France, Georgia, Greece, Iran, Iraq, Lebanon, Syria, Turkey, Uruguay, and the United States of America.
Groups of Brethren assemblies exist in Armenia, Lebanon, Syria, the United States, and Australia.