- as you mentioned the Ira was/were terrrorist organisation , but it was not that important cause they were not Muslims....
- genocide on Jews in WWII , but hey they were no Muslims so it doesnt count ......
- genocide in Yuguslavya , but they they Killed more then 100K Muslims, but hey they were Muslim so is no bad
In Rwanda, it was a racial issue and it was not related to religion. The IRA was also a racial organization, which had nothing to do with religion. And regarding the genocide of Jews during the WW2, you are forgetting the most important fact. Hitler decided to exterminate the Jews, after the grand mufti of Jerusalem urged him to do so. His initial plan was just to deport them. And in the Balkan wars, a majority of the victims were Christians (both Serbs and Croats).
Ireland has a long history of conflict between protestants and catholics. Ireland was brought into Catholicism in the 4th century, but then a King of England decided to start his own brand of religion and bingo, we had protestants. Afterwards, conflict between Ireland and England was of course, between Catholics and Protestants.
Can the actions of the IRA then be considered "religious terrorism?" I'm really skeptical about that, because the goals of the two sides were completely political, not religious.
Wikipedia has a good article on "religious terrorism." I believe it is especially important for people in closed societies, such as a Muslim-dominant culture, to read reasonably unbiased articles such as Wikipedia.
https://en.wikipedia.org/wiki/Religious_terrorism