Rougier's conventionalist philosophical position naturally led him to oppose Neo-Thomism, which had been the official philosophy of the Roman Catholic Church since the 1879 encyclical Aeterna Patris but was gaining particular momentum during the 1920s and 1930s.
Rougier's objections to Neo-Thomism were not merely philosophical, however, but formed part of a general opposition to Christianity that he had already begun to develop during his adolescence under the influence of Ernest Renan.