Catholic Church in Ireland
In the 2016 Irish census 78.3% of the population identified as Catholic in Ireland; numbering approximately 3.7 million people. Unlike Catholics in the United States, Ireland has seen a significant decline from the 84.2% who identified as Catholic in the 2011 census.
Catholic Church in Ireland
The Roman Empire never reached Ireland; so when the Edict of Milan in 313 AD allowed tolerance for the Levantine-originated religion of Christianity and then the Edict of Thessalonica in 380 AD enforced it as the state religion of the Empire; covering much of Europe (including Roman Britain); the indigenous Indo-European pagan traditions of the Gaels in Ireland remained normative. Aside from this independence, Gaelic Ireland was a highly decentralised tribal society, so mass conversion to a new system would prove a drawn out process.