St Peter's Cathedral, Rome

Pope Pius IX responded to modern challenges of Deism, pluralism, and political revolutions by reenforcing the authority of the Catholic Church. First: in 1854, Pius IX declared the Dogma of the Immaculate Conception of the Virgin Mary, which meant that Mary was free from original sin. This pronouncement reasserted the supernatural dimensions of faith and stimulated Catholic devotional life. Second: in 1864 the Syllabus of Errors condemned such "errors" as the separation of church and state, socialism, rationalism, and liberalism. Third: Pius IX convened the Vatican Council of 1869-70, which approved the doctrine of papal infallibility. Almost a century later, Vatican II would pursue a different strategy in relation to modernity.