An unexpected wave of opposition preceded the opening of civil marriage to same-sex couples in France in 2013. Opponents have been actively campaigning, holding some of the biggest demonstrations of the last thirty years, hindering successfully the adoption of significant parts of the Marriage Bill. This counter-movement also jeopardized the bill on transgender people’s status and further progress on issues related to gender and sexual equality, and currently targets the “ideology of gender”, and the teaching of gender in French schools. They depict “gender” as an extremely dangerous weapon used by feminist and LGBT scholars and activists. Interestingly, this opposition notion of “ideology of gender” can be traced back to the Vatican in the early 2000s. Therefore, after presenting the main features of this Vatican discourse, this paper will highlight its centrality in recent French debates and explain why it has been more successful in this country than elsewhere.