From Plus IX to John Paul II

Already in the painful and glorious days of the pontificate of Pius IX (1846‑1878), the collections of pontifical documents showed a radical and irremediable opposition between the traditional doctrine of the Church on one hand and the sentimental daydreams of utopian communism and the rancorous and pedantic assault of scientific communism, or Marxism, on the other.

This incompatibility became all the more pronounced during subsequent pontificates, as reflected, for example, in the polished and precise affirmation of Pius XI in the encyclical Quadragesimo Anno of 1931: "Socialism ... is founded upon a doctrine of human society peculiarly its own, which is opposed to true Christianity. 'Religious Socialism,' 'Christian Socialism,' are expressions implying a contradiction in terms. No one can be at the same time a sincere Catholic and a true Socialist: (Acta Apostolicae Sedis, vol. 23, p. 216). Yet more notable is the famous decree of 1949 forbidding Catholics to collaborate with communism, certain forms of collaboration falling under pain of excommunication. Issued by the Sacred Congregation of the Holy Office, the decree was promulgated by order of Pius XII.

Such pontifical acts intended to prevent Catholics from joining communist ranks, as well as to stop communists from infiltrating Catholic circles under the pretext that certain socioeconomic problems called for mutual collaboration.

The latter was particularly important, since, by extending their hand to Catholics ("the policy of the extended hand") in this fallacious collaboration avowed communism and especially useful innocents of all stripes entered into conviviality with Catholics. This created a propitious climate for enticing considerable numbers of the faithful to Marxist philosophy and action.