Book excerpt: After decades of steady progress in terms of gender and sexual rights, several parts of Europe are facing new waves of resistance to a so-called ‘gender ideology’ or ‘gender theory’. Opposition to progressive gender equality is manifested in challenges to marriage equality, abortion, reproductive technologies, gender mainstreaming, sex education, sexual liberalism, transgender rights, antidiscrimination policies and even to the notion of gender itself. This book examines how an academic concept of gender, when translated by religious organizations such as the Roman Catholic Church, can become a mobilizing tool for, and the target of, social movements. How can we explain religious discourses about sex difference turning intro massive street demonstrations? How do forms of organization and protest travel across borders? Who are the actors behind these movements? This collection is a transnational and comparative attempt to better understand anti-gender mobilizations in Europe. It focuses on national manifestations in eleven European countries, including Russia, from massive street protests to forms of resistance such as email bombarding and street vigils. It examines the intersection of religious politics with rising populism and nationalistic anxieties in contemporary Europe.