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 XIThis power becomes particularly irresistible when exercised by those who, because they hold and control money, are able also to govern credit and determine its allotment, for that reason supplying, so to speak, the lifeblood to the entire economic body, and grasping, as it were, in their hands the very soul of production, so that no one dare breathe against their will.
Pope Pius XIMan cannot be exempted from his divinely-imposed obligations toward civil society, and the representatives of authority have the right to coerce him when he refuses without reason to do his duty. Society, on the other hand, cannot defraud man of his God-granted right... Nor can society systematically void these rights by making their use impossible.
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 XI