How does religion maintain or challenge discourses on national identity? What are the roles that religion plays on all sides – from Islamophobia of the radical right to the Christian alliances on both sides of the Atlantic, to the Islamic beliefs and practices of European citizens as well as migrant communities – in the constitution of Fortress Europe? Are there any alliances shaping between belief and unbelief on either side of the battle for the future of Europe? These questions and more motivate the chapters in this timely interdisciplinary collection, with contributions focusing on diverse contexts throughout Europe involving a broad range of religious identifications and actors.