The church had already fallen into ruins by 1622, according to the Royal Commission records, marking the end of its active life as a place of worship. Its decline coincided with broader shifts in local religious practice; by 1706, the chancel of nearby Rathmullan priory had been consecrated as the new parish church, leaving Killygarvan to moulder in peaceful obscurity. Contemporary accounts from that year describe it as having been “long deserted”, suggesting its abandonment stretched back considerably further than the official records indicate.

Today, the ruined church sits within a graveyard that continues to serve the local community, creating an intriguing juxtaposition between the abandoned sacred building and the active burial ground that surrounds it. This ongoing use ensures the site remains connected to local memory and tradition, even as the church itself stands as a hollow shell. The graveyard’s continued function has likely helped preserve what remains of the church structure, protecting it from complete obliteration whilst maintaining its place in the landscape.

The site forms part of County Donegal’s rich archaeological heritage, documented in the comprehensive Archaeological Survey of County Donegal, which catalogues field antiquities from the Mesolithic Period through to the 17th century. Killygarvan Old Church represents just one of many ecclesiastical ruins scattered across the county, each telling its own story of faith, community, and eventual abandonment as populations shifted and religious practices evolved over the centuries.