If Socialism, like all errors, contains some truth (which, moreover, the Supreme Pontiffs have never denied), it is based nevertheless on a theory of human society peculiar to itself and irreconcilable with true Christianity. Religious socialism, Christian socialism, are contradictory terms; no one can be at the same time a good Catholic and a true socialist.
Pope Pius XICommunism teaches and seeks two objectives: unrelenting class warfare and the complete eradication of private ownership.
Pope Pius XIIt is not possible for Christians to take part in anti-Semitism. We are Semites spiritually.
Pope Pius XIIn his laborious efforts to attain mountaintops, where the air is lighter and purer, the climber gains new strength of limb. In the endeavor to over come obstacles of the way, the soul trains itself to conquer difficulties; and the spectacle of the vast horizon, which from the highest crest offers itself on all sides to the eyes, raises his spirit to the Divine Author and Soverign of Nature.
Pope Pius XIWhen once men recognize, both in private and in public life, that Christ is King, society will at last receive the great blessings of real liberty, well-ordered discipline, peace and harmony.
Pope Pius XIIn the first place, it is obvious that not only is wealth concentrated in our times but an immense power and despotic economic dictatorship is consolidated in the hands of a few, who often are not owners but only the trustees and managing directors of invested funds which they administer according to their own arbitrary will and pleasure. This dictatorship is being most forcibly exercised by those who, since they hold the money and completely control it, control credit also and rule the lending of money.
Pope Pius XI