The article studies the perception of Modernism by the Catholic Church as a movement within the clerical structure and philosophy that existed during the 19-20th centuries in the framework of general skepticism and rejection of tradition, prioritization of individualism, formal equality, faith in inevitability of social, scientific and technological progress, rationalization and professionalization. A distinctive feature of this movement is the participation of the priests themselves, especially in France and Italy. The object of research is the Catholic political doctrine during the pontificate of Pius X. Modernist movement in Catholicism, in opinion of many scientists had a decisive impact on the reform direction during the Second Vatican...