Ballyboghil translates roughly as the town of the staff, referring to the Bachall Íosa, a crozier venerated as the staff of Saint Patrick and regarded in medieval Ireland as, in the words of one contemporary source, "the great relicke of Erlonde". That a place would take its identity from the custody of a single object tells you something about what this quiet corner of Fingal once meant in the broader politics of the Irish church.

The story behind the ruins in the graveyard just north of the village runs from early medieval ecclesiastical rivalry through to the violence of the Norman invasion and on into the Reformation. Around 1113, Ceallach, Archbishop of Armagh, secured the town and its surrounding lands apparently in connection with his metropolitanship over Dublin, which had previously acknowledged Canterbury rather than Armagh as its superior authority. The Bachall was held here as a consequence of that arrangement. In 1173, Strongbow besieged the town for four days, killed its defender Mac Goghdane, and on the same day granted the land and the relic to Holy Trinity, Dublin. After Strongbow's death in 1176 and the resolution of a succession dispute at Armagh, Archbishop Gilbert granted the lands to St. Mary's Abbey, and by 1177 the Governor of Dublin, Fitz Adelm, had the relic moved to Holy Trinity for safekeeping, away from competing claimants to the coarbship of Patrick, the hereditary guardianship of Patrician relics. The Bachall remained at Holy Trinity for over three and a half centuries, until Archbishop George Browne, acting under Henry VIII, had it burnt publicly in front of the cathedral in 1538 as an object of superstition.

The church ruins themselves sit in the southern part of the graveyard and are among the more complete medieval remains in Fingal. The walls survive to near their full height, and the western gable carries a triple bell-cote, a small turret of three arched openings, reached by a set of stone steps rising from the top of the south wall. The large east window, roughly 4.5 metres high and 2 metres wide, has sandstone mouldings and a carved female head at the label stop, the decorative termination of the hoodmould above the arch. Inside, arched tomb recesses are set into the west and south walls, and an aumbry, a small wall cupboard once used to store liturgical vessels, survives in the north wall. By 1630, Archbishop Bulkeley's Visitation noted the building was much out of repair and that all the parishioners were recusants, meaning they refused to attend Church of Ireland services, though the church was apparently still in use at that point.