Despite the broadly assumed institutional separation of church and state in contemporary Western politics, there is a trend towards renewed alliances between illiberal interpretations of religion and right-wing populist politics that challenge liberal democracy. This book explores the theoretically and empirically complex ideological, structural, and historical linkage between religion and illiberal politics within a broad range of European states. It shows how political actors apply Christian identity narratives to push exclusionist anti-Muslim politics, while simultaneously showcasing the ways in which religious actors evolve as illiberal players searching for political allies. This timely volume offers a critical look at a key contemporary issue that challenges assumptions and the reputations of current relationships between church and state.