The sources I relied on are the book of Fr. Edward Lean, The Church before Pilate (https://www.traditionalcatholicpublishing.com/n-pilate.html), chapter 2, Eleison Comments (1587) by Bp. Williamson, and an article by Novus Ordo Watch on Communism (https://novusordowatch.org/2021/02/brief-catholic-critique-of-communism/).
What is Communism if not a system based on Marxism? Marxism is a social, political, and economic theory originated by Karl Marx, which focuses on the struggle between capitalists and the working class. Marx argued that the power relationships between capitalists and workers were inherently exploitative and would inevitably create class conflict. Marx’s method of socioeconomic analysis uses a materialist interpretation of historical development, better known as historical materialism, to understand class relations and social conflict as well as a dialectical perspective to view social transformation.
Bp. Williamson writes that it is very short-sighted to say that economics has nothing to do with religion, because economics (the material relations between men) flow from politics (the human relations between men), and politics (a man’s relations with his fellow-men) descend necessarily from his relations with his God (his religion). At this moment The United States has been brought to the brink of a tremendous economic crisis, and with the USA, the rest of the world.
Fr. Lean identifies Communism as “the most uncompromising enemy of Catholicity”, besides being “the most thorough expression of the partial, incomplete, and somewhat illogical revolts that have marked the course of Christianity from the first years of the Christian era.”
Communism is much more than an economic theory (like Socialism, its weaker form), it is nothing less than a system of “ethics and religion”, as Fr. Leen explains. It seeks to replace, through revolution, the entire social order. Whatever contributes to this goal, is morally acceptable to the Communist, who holds the error that “the end justifies the means”.
The true Popes (not the antipopes of Vatican II) have strongly condemned Communism (and even Socialism), for example, in these magisterial pronouncements:
Pope Leo XIII, Encyclical Quod Apostolici Muneris on Socialism (1878)
Pope Leo XIII, Encyclical Rerum Novarum on Capital and Labor (1891)
Pope Pius XI, Encyclical Quadragesimo Anno on the Reconstruction of the Social Order (1931)
Pope Pius XI, Encyclical Divini Redemptoris on Atheistic Communism (1937).
My private opinion is that Pope Pius XI is the author of the strongest and most clear documents in condemning political errors. He was the one that also condemned Nazism.
Novus Ordo Watch has pointed out that the Church’s condemnation of Communism is not an endorsement of Capitalism. Although not intrinsically evil like Communism, Capitalism tends to corrupt the legitimate quest for making a profit by turning it not only into an end in itself but into the highest of all ends to be sought ferociously, even at the expense of people’s rights and the common good.
Some dispute the statement that “Capitalism is not intrinsically evil”. To support this, they refer to its origins. It found its roots in the intensely individualistic spirit of Protestantism, which transferred its anti-authoritative ideas from the realm of religion into the realm of political and social thought. First and foremost, it borrows the distinctive Calvinist doctrine that a successful and prosperous career is a probable outward sign suggesting election (i.e. predestination to Heaven). Others state that Capitalism involves an internal tension, a paradox, in its very essence. All capitalists are motivated by profit so they aim simultaneously at generating greater productivity at lower costs. This means lower wages. The consequence of all this is that the people who produce profit suffer economical hardship. Even Pope Pius IX condemns the final stage of thys system: “No other forces are to be recognized except those which reside in matter, and all the rectitude and excellence of morality ought to be placed in the accumulation and increase of riches by every possible means, and the gratification of pleasure.” (Error #58, Syllabus of Errors, 1864.)
The following facts are blurring the difference between Capitalism and Socialism even further. Capitalism at its most advanced stage means that an entire country is practically owned by one company (or only a few companies, acting in sync.) In socialism, this “company” happens to be the state. Hence some often interchange the term “state socialism” with “state capitalism”, while referring to the economic systems of Marxist–Leninist states such as the Soviet Union to highlight the role of state planning in these economies. These people refer to socialism more commonly as “state capitalism”. In Capitalism the voting process is fairer, but the figureheads you are voting for are merely figureheads lacking any real power which belongs to the establishment one is not voting for. So there is even no need to rig the elections. (Figureheads may not overstep their limits without serious consequences, as in the case of JFK. Bush and Clinton made very different promises, but acted almost the same way.) In socialism, one is voting for are the real leaders, but elections are completely rigged. So in their advanced stage, both end up being the same. So these systems, Communism, Socialism, and Capitalism are false alternatives.
Moreover, even the distinction between the political left (Communism, Socialism) and the political right (Fascism) is fake. The truly ironic fact is that the term “nazi” comes from the German word “Nationalsozialismus” which means national Socialism, a name some Fascists gave to themselves, in open admission that they copied Socialism. (Some would say that it is Socialism that copied the right, but the truth is that the so-called left has come earlier into existence and has not changed substantially.) The only difference between the two supposed extremes is merely the fact that while Socialism deifies humankind, national Socialism deifies merely the nation. This difference is quite insignificant. So competent people consider them false alternatives and consign both of them to the extreme left.
One might ask if these are false alternatives, what is the real one? This is called “Distributism”. Distributism is the social-economic philosophy holding that private property, while indeed licit, even vital, must be widely dispersed for the good of society. It favors small property holders, small business owners, and tradesmen who own their machinery and other tools; while it doesn’t favor large governments and corporations which frequently hold significant economic power. As some would falsely understand, the term “widely dispersed” doesn’t mean that one must distribute his assets. True popes recommend these principles of Catholic social teaching, especially Pope Leo XIII in his encyclical Rerum Novarum and Pope Pius XI in Quadragesimo Anno. This system was devised in the late nineteenth and early twentieth century. It began in England, in the early twentieth century. Its founders were Chesterton and Belloc.