Whether considered as a doctrine, or as an historical fact, or as a movemement, socialism, if it really remains socialism, cannotbe brought into harmony with the dogmas of the Catholic church.... Religious socialism, Christian socialism, are expressions implying a contradiction in terms.
Pope Pius XIFor them (the peoples of the Soviet Union) We cherish the warmest paternal affection. We are well aware that not a few of them groan beneath the yoke imposed on them by men who in very large part are strangers to the real interests of the country. We recognize that many others were deceived by fallacious hopes. We blame only the system with its authors and abettors who considered Russia the best field for experimenting with a plan elaborated years ago, and who from there continue to spread it from one of the world to the other.
Pope Pius XIIf 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 XIThis organic conception of society, the only vital conception, combines a noble humanism with the genuine Christian spirit, and it bears the inscription from Holy Writ which St. Thomas has explained: "The work of justice shall be peace"; a text applicable to the life of a people whether it be considered in itself or in its relations with other nations.
Pope Pius XIFurthermore, in this one Church of Christ no man can be or remain who does not accept, recognize and obey the authority and supremacy of Peter and his legitimate successors.
Pope Pius XIFor they have always unanimously maintained that nature, rather the Creator Himself, has given man the right of private ownership not only that individuals may be able to provide for themselves and their families but also that the goods which the Creator destined for the entire family of mankind may through this institution truly serve this purpose.
Pope Pius XI