Religion in the Republic of Ireland
The predominant religion in the Republic of Ireland is Christianity, with the largest church being the Roman Catholic Church. The Irish constitution says that the state may not endorse any particular religion and guarantees freedom of religion.
Culture of Ireland
Christianity in the form of both Roman Catholicism and Protestantism is the most widely practiced religion in Ireland. Christianity was brought to Ireland during or prior to the 5th century and its early history among the Irish is in particular associated with Saint Patrick, who is generally considered Ireland's patron saint. The Celtic festival of "Samhain", known as Halloween, originated in Ireland and is now celebrated all over the world.