How do we situate manifestations of religious party radicalism within a useful comparative political framework, and what factors influence how these parties operate within their respective political systems? In The Politics of Religious Party Change, A. Kadir Yildirim explores the impact of religious institutional hierarchy and authority structures on the development of religious parties in differing contexts in Europe and the Middle East and North Africa. While examining Catholic parties in Germany, Italy, and Belgium and Sunni Islamist political movements in Turkey, Egypt, and Tunisia, he argues that the nature of institutional religious authority in Catholic communities caused political party activism on behalf of Catholics to shed its “confessional dilemma” (3) in ways unavailable to Sunni Islamist political movements. Yildirim’s argument rests on the distinction that Catholicism’s authoritative institutional hierarchy made it difficult for Catholic political parties to lay claim to their own spiritual authority; thus, Catholic parties were able to focus on representative political activism and had less incentive to be antisystem. However, because spiritual authority within Sunni Islam is more diffuse and less hierarchical, Yildirim argues that Islamist political movements have tended to establish themselves both as a source of spiritu