Please check your ignorance.

[Richard Jenkins (1997). Rethinking Ethnicity: Arguments and Explorations. SAGE Publications. p. 120]

"The conflict was primarily political and nationalistic, fuelled by historical events.[27] It also had an ethnic or sectarian dimension,[28] although it was not a religious conflict.[11][29]" 

"It should, I think, be apparent that the Northern Irish conflict is not a religious conflict... Although religion has a place—and indeed an important one—in the repertoire of conflict in Northern Ireland, the majority of participants see the situation as primarily concerned with matters of politics and nationalism, not religion. And there is no reason to disagree with them."