Catholicism was the religion of most people who advocated joining the Republic; but most of the unionists, who were greater in number and preferred the status quo of staying in the UK, were Protestants.
主張加入愛爾蘭的民族基本教義派多屬天主教徒；至於人數較多、主張保持現狀、留在英國的聯合派，則多屬新教徒。