Why did religion cause disagreements between Ireland and Britain apex?

Religion caused disagreements between Ireland and Britain primarily due to the historical conflict between Protestantism and Catholicism. In Ireland, the majority of the population was Catholic, while Britain, particularly England, was predominantly Protestant. This religious divide exacerbated political tensions, leading to discrimination against Catholics in Ireland and fostering resentment. Additionally, the Protestant Ascendancy in Ireland sought to maintain control, further deepening the divide and contributing to the broader conflict over national identity and governance.