History of Roman Catholicism in Ireland

This article details the history of Christianity in Ireland. Ireland is an island to the north-west of continental Europe. Politically, Ireland is divided between the Republic of Ireland, which covers just under five-sixths of the island, and Northern Ireland, a part of the United Kingdom, which covers the remainder and is located in the north-east of the island. Roman Catholicism is the largest religious denomination, representing over 73% for the island and about 87% of the Republic of Ireland.

The introduction of Christianity to Ireland dates to sometime before the 5th century, presumably in interactions with Roman Britain. Christian worship had reached pagan Ireland around 400 AD. It is often misstated that St. Patrick brought the faith to Ireland, but it was already present on the island before Patrick arrived. Monasteries were built for monks who wanted permanent communion with God. The lengths they went to for tranquility are evident from the monastery of Skellig Michael. Via Aidan, Christianity spread among the Picts and Northumbrians.

Scholars have long considered the term "Celtic Church" to be inappropriate for describing Christianity among Celtic-speaking peoples, since this would imply a notion of unity, or a self-identifying entity, that did not exist. As Paul Wormald explained, "One of the common misconceptions is that there was a 'Roman Church' to which the 'Celtic' was nationally opposed." Celtic-speaking areas were part of Latin Christendom as a whole, wherein a significant degree of liturgical and structural variation existed, along with a collective veneration of the Bishop of Rome that was no less intense in Britain and Ireland. Some scholars have chosen to apply the term "Insular Christianity" to this Christian practice that arose around the Irish Sea.

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