Integrism (French: Intégrisme) is a term coined in 19th and early 20th century polemics within the Catholic Church, especially in France, as an epithet to describe those who opposed the "modernists" who had sought to create a synthesis between Christian theology and the liberal philosophy of secular modernity. Integrism is often referred to as Catholic Integralism.
Integrists taught that all social and political action ought to be based on the Catholic Faith. They rejected the separation of church and state, arguing that Catholicism should be the proclaimed religion of the state.
Many of the positions of integrism on the necessity of the subordination of state to the Church go back to the teachings of medieval popes such as Pope Gregory VII and Pope Boniface VIII. But Integrism in the strict sense came about as a reaction against the political and cultural changes which followed the Enlightenment and the French Revolution. The nineteenth century papacy challenged the growth of liberalism (with its doctrine of popular sovereignty) as well as new scientific and historical methods and theories (which were thought to threaten the special status of the Christian revelation). Pope Pius IX condemned a list of liberal and Enlightenment ideas in his Syllabus of Errors. The term Integrism did not, however, became popular till the time of Pope St. Pius X, whose papacy lasted from 1903 to 1914. Supporters of Pius X's encyclical Pascendi dominici gregis, which condemned Modernism, called themselves Catholiques intégraux (integral Catholics), from which the word intégrisme (Integrism) and intégralisme (Integralism) were derived.