This book explores what the European Union (EU) does to religion and what religion does to the EU. Europe is secularising, and meanwhile struggling with a renewed salience of religion as a political and cultural resource instrumentalised for various purposes. The EU as a whole, and especially the European Parliament as the representative body reflecting the diversity and conflicts of national societies, face this challenge in their everyday functioning. This book presents the second wave of an unprecedented survey studying what members of the European Parliament (MEPs) believe, and what they do with these beliefs. Research questions include: Are European elites more secularised than EU citizens and national politicians? What is the impact of religion on the political socialisation of MEPs and, conversely, what is the influence of MEPs on religion? How do religion, coalition- and decision-making interact at the European level? What happens in the triangular relationship between nation,