“Driven by religious reasons, the Church has always condemned the various systems of marxist socialism, and still condemns them today as it is its duty and permanent right to preserve men from currents of thought and influences that endanger their eternal salvation. But the Church cannot ignore or pretend not to see that the worker, in the effort to improve his station, collides with any spirit that, far from conforming to nature, contrasts itself with the order of God and the design he assigned to earthly goods. As false, objectionable, and dangerous those other [socialist] paths have been and still are today, who, especially if priest or Christian, can remain deaf to the yelling rising from the deep which, in a world created by a just God, cries out for justice and a spirit of fraternity? Such a thing would be a guilty and unjustifiable silence before God and, besides, contrary to the inspired sense of the apostle, who, as he preaches we must be resolute against error, also knows that we must remain full of attention towards those who err, with an open soul to understand their aspirations, hopes, and reasons.
When he blessed our forefathers, God said to them: “Grow and multiply, and fill the land and dominate it” (Gn 1:28). To the first chief of family, he said: “You shall eat the bread with the sweat of your face” (Gn 3:19). The dignity of the human person demands, as the natural foundation for living, the right to the use of earthly goods. To such a right corresponds the fundamental obligation to provide private property to all. The positive juridical norms, regulating private property, can change and concede a more or less limited use; but if they wish to contribute to the peace of the community, they must not allow the worker, who is and always will be a father of family, to be condemned to economic dependence or slavery, irreconcilable with his rights as a person.
Whether this servitude comes from the arrogance of private capital, or the power of the State, its effect does not change. On the contrary, under the pressure of a State that all dominates and regulates completely both public and private life, penetrating even into the field of conceptions, and persuasions, and conscience, similar lack of freedom can have even more onerous consequences, as experience manifests and testifies to.”
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Venerable Pope Pius XII
1942 Christmas Radiomessage, #23-25
(my translation from the Portuguese version at vatican.va)