Contrary to what might be expected, there is no scholarly consensus on the role religion plays in motivating religious terrorism. This article is one of a series that explores why this is the case, examining the relevant conceptual and substantive issues. After introducing the fundamental explanatory challenges that frame the debate, the article sketches a typology of the prevailing interpretive options, and then critically examines one influential option: the claim that social relationships, small group dynamics, and social identity processes are far more important than religious or political ideologies in explaining why people engage in terroristic violence. The article then argues that the findings of a set of interviews with Western foreign fighters in Syria and Iraq, and the friends and families of such fighters, alternatively indicates that religiosity plays a more consequential motivational role, at least for jihadists, than the research literature tends to recognize.

Keywords: Terrorism, religion, radicalization, jihadist, social identity