The western gable is the only part still standing to any height; the rest of the church has collapsed to its lower courses, leaving a footprint roughly nine metres long and four and a half metres wide. No dressed stonework survives, no visible doorway, no windows. A narrow inlet sixty metres to the north was recorded on the 1837 Ordnance Survey map as Church Harbour, which suggests the building was a known landmark even as it crumbled, and that boats were still finding their way to it by a name that remembered its purpose.

The island's religious life appears to stretch back at least to the early medieval period, when a monastery was reputedly founded here by St. Laobhán. The genealogies surrounding him are extravagant even by the standards of early Irish hagiography: he was said to be one of 47 children born to a woman named Cuman, who was a maternal aunt of St. Brighid of Kildare and whose womb had allegedly been blessed by St. Patrick. His feast day fell on the 9th of August. By 1103, the Annals of the Four Masters were recording the death of a figure described as the Lector Ua Connmhaigh, identified as being of the family of Inis-mor, which places a community of some learning on the island at that date. Later, probably before 1170, a priory of Augustinian Canons, a religious order that followed the Rule of St. Augustine and was widely established across medieval Ireland, was founded here according to the antiquary James Ware. After the dissolution of the monasteries under the Tudors, the island's lands passed to Richard Barnwell, and by 1641 they were held jointly by Lord Viscount Dillon, Gerald Dillon, and John Dillon, the ecclesiastical world having given way entirely to the landed one.