The American Enterprise Institutes’ Mark J. Perry writes:
Some historical perspective on what four of the last five previous popes had to say about socialism over the last 50 years (emphasis added)……
1. Pope John XXIII (1958-1963)
Pope Pius XI further emphasized the fundamental opposition between Communism and Christianity, and made it clear that no Catholic could subscribe even to moderate Socialism. The reason is that Socialism is founded on a doctrine of human society which is bounded by time and takes no account of any objective other than that of material well-being. Since, therefore, it proposes a form of social organization which aims solely at production; it places too severe a restraint on human liberty, at the same time flouting the true notion of social authority.
~Radio message to the Katholikentag of Vienna, September 14, 1952 in Discorsi e Radiomessaggi, Vol. XIV, p. 314
2. Pope Paul VI (1963-1978)
Too often Christians attracted by socialism tend to idealize it in terms which, apart from anything else, are very general: a will for justice, solidarity and equality. They refuse to recognize the limitations of the historical socialist movements, which remain conditioned by the ideologies from which they originated.
~Apostolic Letter Octogesima Adveniens, May 14, 1971, n. 31
3. Pope John Paul II (1978-2005)
The fundamental error of socialism is anthropological in nature. Socialism considers the individual person simply as an element, a molecule within the social organism, so that the good of the individual is completely subordinated to the functioning of the socio-economic mechanism. Socialism likewise maintains that the good of the individual can be realized without reference to his free choice, to the unique and exclusive responsibility which he exercises in the face of good or evil. Man is thus reduced to a series of social relationships, and the concept of the person as the autonomous subject of moral decision disappears, the very subject whose decisions build the social order. From this mistaken conception of the person there arise both a distortion of law, which defines the sphere of the exercise of freedom, and an opposition to private property. A person who is deprived of something he can call “his own,” and of the possibility of earning a living through his own initiative, comes to depend on the social machine and on those who control it. This makes it much more difficult for him to recognize his dignity as a person, and hinders progress towards the building up of an authentic human community.
Encyclical Centesimus Annus − On the 100th anniversary of Pope Leo XIII’s Rerum Novarum, May 1, 1991, n. 12
4. Pope Benedict XVI (2005 – 2013)
The State which would provide everything, absorbing everything into itself, would ultimately become a mere bureaucracy incapable of guaranteeing the very thing which the suffering person—every person—needs: namely, loving personal concern. We do not need a State which regulates and controls everything, but a State which, in accordance with the principle of subsidiarity, generously acknowledges and supports initiatives arising from the different social forces and combines spontaneity with closeness to those in need. The Church is one of those living forces.
~Encyclical Letter of Pope Benedict XVI