Since the 19th century, there have been attempts to reconcile Catholicism with modern culture, specifically an understanding of the Bible and Sacred Tradition in light of the historical-critical method and new philosophical and political developments of the late 19th and early 20th centuries.

The term modernism—generally used by its critics rather than by adherents of positions associated with it—came to prominence in Pope Pius X's 1907 encyclical Pascendi Dominici gregis, where he condemned modernism as "the synthesis of all heresies".

Writing in the Catholic Encyclopedia in 1911, the Jesuit Arthur Vermeersch gave a definition of modernism in the perspective of the Catholic heresiology of his time:"In general we may say that modernism aims at that radical transformation of human thought in relation to God, man, the world, and life, here and hereafter, which was prepared by Humanism and eighteenth-century philosophy, and solemnly promulgated at the French Revolution."The modernist movement was influenced and accompanied by Protestant theologians and clergy like Paul Sabatier and Heinrich Julius Holtzmann. On the other hand, modernist theologians were critical of Protestant theology and engaged in Catholic apologetics against a Protestant understanding of Christianity, as in the famous attack of Alfred Loisy in L'Évangile et l'Église (1902) on Adolf von Harnack's Das Wesen des Christentums (1900). The modernist movement has a parallel in the Church of England where the journal The Modern Churchman was founded in 1911.

The controversy on modernism was prominent in French and British intellectual circles and to a lesser extent in Italy, but in one way or another concerned most of Europe and the Americas. Pope Pius X saw modernism as a universal threat which required a global reaction.

Dimensions of the controversy over modernism

Although the so-called modernists did not form a uniform movement, they responded to a common grouping of religious problems which transcended Catholicism alone around 1900: first of all the problem of historicism, which seemed to render all historical forms of faith and tradition relative; secondly, through the reception of modern philosophers like Immanuel Kant, Maurice Blondel, and Henri Bergson, the neo-scholastic philosophical and theological framework set up by Pope Leo XIII had become fragile. The assertion that objective truth is received subjectively is fundamental for the entire controversy. This focus on the religious subject engendered a renewed interest in mysticism, sanctity and religious experience in general. The aversion against a religious "extrinsicism" also led to a new hermeneutics for doctrinal definitions which were seen as secondary formulations of an antecedent (immanent) religious experience (George Tyrrell; cfr. also the Christian personalism of Lucien Laberthonnière).

The controversy was not restricted to the field of philosophy and theology. On the level of politics, Christian Democrats like the layman Marc Sangnier in France and the priest Romolo Murri in Italy, but also the left wing of the Centre Party and the Christian Unions in Germany, opted for a political agenda which was no longer completely controlled by the hierarchy. Pope Pius X reacted by excommunicating Murri in 1909, by dissolving Sangnier's Le Sillon movement in 1910, and by issuing the encyclical in 1912 which clearly favoured the German Catholic workers' associations over and against the Christian Unions. Furthermore, antimodernists like Albert Maria Weiss , and the Swiss Caspar Decurtins, which were both favoured by Pius X, would even find "literary modernism" on the field of the Catholic belles-lettres which did not meet their standards of orthodoxy.

In the eyes of the antimodernist reaction, the "modernists" were a uniform and secret sect within the Church. From a historical perspective, one can discern networks of personal contacts between "modernists", especially around Friedrich von Hügel and Paul Sabatier. On the other hand, there was a great diversity of opinions within the "movement", from people ending up in rationalism (e.g. Marcel Hébert, Albert Houtin, Alfred Loisy, Salvatore Minocchi, and Joseph Turmel) to a mild religious reformism, even including neo-scholastic theologians like Romolo Murri. This perception of a broad movement from left to right was already shaped by the protagonists themselves.

Terminology

The term Liberal Catholicism originally designated a current of thought within the Catholic Church that was influential in the 19th century, particularly in France, that aimed to reconcile the church with liberal democracy. It was largely identified with French political theorists such as Felicité Robert de Lamennais, Henri Lacordaire, and Charles Forbes René de Montalembert.Bury, J.P.T., "Religion and Relations of Churches and States", The New Cambridge Modern History, Vol. 10, CUP Archive, 1960 In the second half of the 19th century the term was also applied to theologians and intellectuals like Ignaz von Döllinger, St. George Jackson Mivart, John Zahm, and Franz Xaver Kraus who wanted to reconcile the Catholic faith with the standards of modern science and society in general.

In 1881, the Belgian economist Charles Périn, a conservative Catholic layman, published a volume titled ("Modernism in the Church according to the unpublished letters of La Mennais"). Périn was the first author to use the term modernism in a Catholic context – before him the Dutch Calvinist Abraham Kuyper had attacked the rationalist German theology of the Protestant Tübingen School as "modernism" (, 1871). For Périn, 'modernism' was a label for the attempts of Liberal Catholics to reconcile Catholicism with the ideals of the French Revolution and of democracy in general. He saw a danger that humanitarian tendencies in secular society would be received within the Catholic Church. This "social" definition of Catholic modernism would be taken up again later by Integralism. Périn's usage of the term modernism was accepted by the Roman journal of the Jesuits, the semi-official , which added the aspect of an exaggerated trust in modern science to this concept. When five exegetical books of the French theologian Alfred Loisy were placed on the Index of Forbidden Books in December 1903, the Holy See’s official paper L'Osservatore Romano distinguished between "modernity" and "modernism", which entailed heresy in religion, revolution in politics, and error in philosophy. The term modernism now began to replace older labels like 'Liberal Catholicism' or (especially in Germany) 'Reform Catholicism'.

The connection between 'Liberal Catholicism' and 'modernism' has been subject to controversial discussion. In 1979, Thomas Michael Loome stressed the continuity between the two and talked of a "vertical dimension" of the modernist controversy. This "invention of tradition" was criticized – amongst others – by Nicholas Lash. It is clear, however, that the Joint Pastoral of the English episcopate against "Liberal Catholicism" (December 1900) did not only react on St. George Jackson Mivart, but also on the writings of the later "modernist" George Tyrrell. The letter had been prepared in Rome and was inspired by Rafael Merry del Val who became Tyrrell's chief opponent under Pius X. Furthermore, "modernists" like Tyrrell compared their own difficulties after the publication of with the difficulties of "liberal Catholics" like Ignaz von Döllinger after Vatican I. In December 1907, Tyrrell wrote to a German correspondent: "Is it not time to reconsider the pseudo-council of 1870 and to ask whether the Alt-Katholiks were not, after all, in the right? etc. ["You will know them by their fruits"; Matthew 7:16] may surely be used as a criterion of Ultramontanism. Individuals, like myself, can afford to stand aloof as Döllinger did. But can multitudes live without sacraments and external communion? And yet now no educated man or woman will be able to remain in communion with Pius X." Tyrrell was also inspired by the posthumous publication of Lord Acton's History of Freedom and Other Essays in 1907.

History of the modernist controversy Although the so-called "Modernist Crisis" is usually dated between 1893 (the publication date of Pope Leo XIII's encyclical ) and 1914 (the death of Pope Pius X), the controversy had, and continues to have, both a pre-history and a post-history.

Pre-history: Liberal Catholicism in the 19th century

With notable exceptions like Richard Simon or the Bollandists, Catholic studies in the 17th, 18th and 19th centuries had tended to avoid the use of critical methodology because of its rationalist tendencies. Frequent political revolutions, the bitter opposition of "liberalism" to the Church and the expulsion of religious orders from France and Germany had made the church understandably suspicious of the new intellectual currents.

Following the French Revolution and the subsequent coming to power of the Conservative Order, the Magisterium had enacted harsh condemnations against liberalism, rationalism, pantheism, panentheism, deism, indifferentism, socialism, communism and other popular philosophies. Non-Catholic Bible translations and interpretations had been met with similar scorn.

In 1863, Ernest Renan published (Life of Jesus). Renan had trained for the priesthood before choosing a secular career as a philologist and historian. His book described Jesus as – a man, no doubt extraordinary, but only a man. The book was very popular, but cost him his chair of Hebrew at the Collège de France. Among Renan's most controversial ideas was that "a miracle does not count as a historical event; people believing in a miracle does." Renan's Jesus is a man of simple piety and almost unimaginable charisma whose main historical significance was his legion of followers.

In the same year, Church historian Ignaz von Döllinger invited about 100 German theologians to meet in Munich (, 1863) to discuss the state of Catholic theology. In his address, "On the Past and Future of Catholic Theology", Döllinger advocated greater academic freedom of theology within the Church, formulating a critique of neo-scholastic theology and championing the historical method in theology.Howard, Thomas Albert. "A Question of Conscience", Commonweal, September 29, 2014 Döllinger's friend Charles de Montalembert gave two powerful speeches at the Catholic Congress in Malines that year too, insisting that the church had to reconcile itself with civil equality and religious freedom.O'Malley, John W. Vatican I: The Council and the Making of the Ultramontane Church Harvard University Press 2019Lecanuet, Edouard 1902, p. 356 : Discours de Malines, 20–21 août 1863, Tome 3 : L'Église et le second Empire.