in Roman Catholic church history, a movement in the last decade of the 19th century and first decade of the 20th that sought to reinterpret traditional Catholic teaching in the light of 19th-century philosophical, historical, and psychological theories and called for freedom of conscience. Influenced by non-Catholic biblical (Bible) scholars, Modernists contended that the writers of both the Old and the New Testaments were conditioned by the times in which they lived and that there had been an evolution in the history of biblical religion. Modernism also reflected a reaction against the increasing centralization of church authority in the pope and the Roman Curia (papal bureaucracy).

In France the movement was closely associated with the writings of Alfred Firmin Loisy (Loisy, Alfred Firmin), who was dismissed in 1893 from his teaching position at the Institut Catholique in Paris for his views about the Old Testament canon. These views, later expressed in La Religion d'Israel (1900; “The Religion of Israel”), and his theories on the Gospels in Études évangéliques (1902; “Studies in the Gospels”) were both condemned by François Cardinal Richard, the archbishop of Paris. In England George Tyrrell (Tyrrell, George), an Irish-born Jesuit priest, was dismissed from his teaching post and from the Jesuits for his views on papal infallibility and for a doctrine that minimized the intellectual element of revelation and thus seemed to contradict the teachings of the First Vatican Council (1869–70). His theories influenced others, notably the French layman Édouard Le Roy. Also in England, a scholar, Baron Friedrich von Hügel (von Hügel, Friedrich, Baron Von Hügel), was critical of some methods of church government and defended the right of Loisy and Tyrrell to publish their views; he did not, however, reject the papacy or share some of Tyrrell's philosophical opinions. In Italy the writings of Loisy and Tyrrell influenced the priest-scholars Ernesto Buonaiuti and Giovanni Semeria, the novelist Antonio Fogazzaro, and other Catholics. In Italy, as also in Germany, concern with reform of church institutions was a more prominent theme than rejection of doctrine.

The reaction of Rome included the suspension or excommunication of certain priests and scholars who were associated with the movement, the placement of books on the Index of Forbidden Books, the establishment in 1903 by Pope Leo XIII of the Pontifical Biblical Commission to monitor the work of Scripture scholars, and the formal condemnation in 1907 in the papal encyclical Pascendi Dominici Gregis and the decree Lamentabili Sane Exitu of the Curia's Holy Office. In order to ensure enforcement, the priest-scholar Umberto Benigni organized, through personal contacts with theologians, a nonofficial group of censors who would report to him those thought to be teaching condemned doctrine. This group, known as Integralists (or Sodalitium Pianum, “Solidarity of Pius”), frequently employed overzealous and clandestine methods and hindered rather than helped the combating of Modernism. On June 29, 1908, Pius X (Pius X, Saint) publicly admitted that Modernism was a dead issue, but at the urging of Benigni on Sept. 1, 1910, he issued Sacrorum antistitum, which prescribed that all teachers in seminaries and clerics before their ordination take an oath denouncing Modernism and supporting Lamentabili and Pascendi.