This essay presents a sketch of a sociological approach to the study of possible links between religion and violence. It aims to avoid two unhelpful positions: the structural social science that denies religion causal status and explains everything by circumstance and the popular commentary that gives too much weight to very specific religious ideas. It suggests that instead of trying to explain rare and exotic political action we look for possible links between large abstract features of religious traditions and key features of the culturally-produced social backgrounds which inform how large groups of people orient themselves to other groups, to the issue of individual rights, and to the legitimacy of the state. The example of the involvement of Protestant fundamentalists in the political violence of Northern Ireland is used to illustrate this approach. The refusal of such fundamentalists to engage in holy war is explained by a combination of circumstances and religious ideas.