Ordnance Survey mappers in 1840 called it St Michael's Church and Garden; by 1920 the same building was recorded as the Baptism Church; the scholar R.A.S. Macalister, writing in 1916, called it St Brigid's church entirely. The building itself measures just 8.5 metres by 5 metres, a single-celled structure that would have held only a small congregation, yet its identity has remained stubbornly contested across two centuries of documentation.

The church was built around the middle of the twelfth century and features a Romanesque doorway at its west end, the rounded-arch style of ornamental stonework that spread across Ireland during the same period. It did not remain in use for long. By the beginning of the thirteenth century it had been abandoned as a place of worship, and its interior was then given over to burial, probably through much of that same century. Excavations carried out between 1970 and 1972 uncovered at least twenty burials, almost all of them extended and oriented east to west in the conventional Christian manner. Two of the dead were women who had died in childbirth. The excavations also revealed that the church had once been slated, with evidence suggesting the slates were brought from elsewhere and trimmed on the island itself. By the early nineteenth century the doorway and west gable had collapsed, and for a period the building was used to shelter animals. The Board of Works eventually rebuilt the fallen west end in 1879 to 1880, though with what the record describes as some small irregularities. Two deeply splayed windows survive, one in the east wall and one in the south wall near where the altar would have stood; the east window has since been robbed of its stonework, leaving only the wide interior splay intact.

Iniscealtra is accessible by boat from Mountshannon on the Clare shore, and the church sits within a subrectangular enclosure roughly ninety metres southwest of the island's round tower. The round tower is the most immediately visible landmark on arrival, and the smaller church requires a short walk across ground shared with several other early medieval remains. The Romanesque doorway, rebuilt as it is, remains the most legible feature at close quarters.