The church has a basic T shaped structure, with two small chapels on either side of the main body of the church. The southern chapel can only be accessed from outside. There is a lot of speculation about the ancient origins of this place of worship; one tradition tells that St Ronan founded the church, before retiring to the Isle of Rona (in legend travelling on the back of a whale).
The church is now in use as a Scottish Episcopal Church. There are ruins of another temple 'Teampall Ronaidh' about 500m north east of Teampall Mholuaidh and remains of another temple 'Teampall Pheadair' are about 2km south west of Teampall Mholuaidh beside the old graveyard near the village of Swainbost.
One of the most enduring traditions associated with the church is its power as a place of healing, especially for those afflicted with mental problems. Many people were brought here in the hope of healing, and even those who could not reach the church sent wooden effigies of their afflicted parts. Captain Dymes who came to Lewis in 1630 recorded that people who could not visit the church "were wont to cut out the portion of their lame arms or legs in wood with the form of their sores and wounds therof and send them to the saint where I have seen them lying on the altar of the chapel.
Perhaps one of the most interesting stories and traditions associated with the church is its links with a god of the sea, Seonaidh. If true the origins of this ceremony may be very old indeed, and may be a lost link with the practices of the pre-Christian islanders.