The IRA is a Marxist organization, like ETA, and both have been active for decades with the PLO and other leftist Islamist groups. It is not Christian and does not pretend to be, except in the sense that it took advantage of a sectarian nationalist conflict in Ireland to grow and become powerful.
ETA's "ideal" socialist paradise was the old Albania, the worst and harshest of the Communist dictatorships; the IRA also aspired to that type of country, but the IRA is more international, probably because of all the money given to it by idiot Americans in their bars, and has become a free-floating school for terrorists everywhere. An IRA "bomb specialist" was arrested in Brazil last year, where he had gone to provide training to a mixed group of leftists and jihadis in the Triple Border area.