Denis was affected by the political turmoils of the time, such as the Dreyfus affair (1894–1906) which divided French society and the art world with Émile Zola and André Gide on one side, defending Dreyfus, and Rodin, Renoir and Denis on the other. Denis was in Rome during most of the events, and it did not affect his friendship with Gide. More significant for him was the movement of the French government to reduce the power of the church, and the decision of the government to officially separate the church and state in 1905. Denis joined the nationalist and pro-Catholic "Action Française" in 1904, and remained a member until 1927, when the group had moved to the extreme right and was formally condemned by the Vatican.