Throughout the centuries, Catholic popes have consistently condemned socialism in every form as contrary God’s will, and therefore against human nature and against the teachings of the Church. In his masterful encyclical of 1937 on Atheistic Communism (Divini Redemptoris), Pope Pius XI reiterated that condemnation. The pope had stated that "no one can be at once a true Catholic and a sincere socialist." The following excerpt from Fr. Denis Fahey’s booklet, The Rulers of Russia (1938) explains:

... This high-taxing, high-spending policy is laid down in innumerable Socialist handbooks as an essential preliminary to the imposition of full Socialism. Private enterprise is to be so crushed with burdens of every sort that it is glad to throw in the sponge and quit....‘Taxation is the chief means,’ says Britain’s Socialist Fabian Society in its Tract No. 127, adding that ‘to the Socialist, the best of governments is that which spends the most.’ Similarly emphatic was a leading American exponent of Socialism, the late Morris Hillquit (a Jew whose real name was Misca Hilkowicz), who pointed out in his Socialism Summed Up (1913) that by high taxes, shorter hours and shorter week, freedom to strike, etc., the owners of businesses could be reduced to the point of being glad to be taken over by the State. Another eminent Jewish Socialist, Professor Laski, of the London School of Economics, is equally strong on ‘the weapon of taxation’....Mr. George Bernard Shaw, eminent British Socialist, puts the bedrock idea of the whole business very bluntly in the British Labour Monthly of October, 1921. He said: ‘Compulsory labour, with death as the final penalty, is the keystone of Socialism.’...In a fully Socialised state, opposition to the ruling clique must from the force of circumstances take the form of underground conspiracy, working secretly until it is strong enough for an open test of strength. Against this danger the ruling clique in turn must protect itself with a gigantic spy service....Russia’s gigantic spy service and perpetual ‘liquidations’ of suspected oppositionists are no accidental features. They are inherent in full Socialism. As to how they work out in practice, a former Bolshevik Commissar of Justice named Steinberg gave the following description in the New York Times of February 23, 1930: ‘ On the one side, we have intoxication with power and a realisation that anything done by him who wields power will go unpunished; and, on the other, fear, depression, silent hatred and sycophancy; the rise of two classes, masters and slaves. In turn the relations among the suspects become themselves perverted. In the struggle to win the favour of the authorities, treachery assumes appalling dimensions. All become slaves with respect to the government, and wolves with respect to one another.’ The fatal defect of Socialism is its utter incompatibility with respect for personality....Human freedom is drowned in an ocean of materialism....The Marxian class-war is intended solely to set the Christians at one another’s throats....The whole trend of Socialism is to deprive Christians of their property and to reduce them to a sub-human, animal status. It puts them in the position the Talmud says it is their destiny to occupy. Finance-Capitalism began the work. Socialism completes it. (Rev. Denis Fahey, C.S.Sp., The Rulers of Russia, 1938, p. 96f.)