The Catholic Church has been an opponent of communism, but that doesn't mean it subscribes to an either/or decision between communism and capitalism. Still, the Church has been consistently opposed to communism dating back to the 19th century.

In May of 1891, Leo XIII issued the encyclical Rerum Novarum. This document is noted as the beginning of the crystallization of modern Catholic social justice thought. It is also a conscious answer to Marx. In it, the pope affirms the need for assistance for the working poor. However, he also rejects communism as an ideology. At the same time, he also rejects unrestricted capitalism, but affirms the right to private property.

This encyclical has been commemorated and updated by other pontiffs. Pius XI issued Quadragesimo Anno in 1931, John XXIII followed with Mater et Magistra in 1961, and John Paul II marked the centennial with Centesimus Annus in 1991. Each pontiff built on the last in delineating Catholic positions on social justice and economics, all of which were unfavorable to communism.

In March of 1937, Pius XI issued the most important document regarding Catholicism and communism--Divini Redemptoris. In it, the basic incompatibilities between the two ideologies are outlined. From section 3:

3. This all too imminent danger, Venerable Brethren, as you have already surmised, is bolshevistic and atheistic Communism, which aims at upsetting the social order and at undermining the very foundations of Christian civilization.

Then we have the outright rejection in sections 12 and 14.

.12. What would be the condition of a human society based on such materialistic tenets? It would be a collectivity with no other hierarchy than that of the economic system. It would have only one mission: the production of material things by means of collective labor, so that the goods of this world might be enjoyed in a paradise where each would "give according to his powers" and would "receive according to his needs." Communism recognizes in the collectivity the right, or rather, unlimited discretion, to draft individuals for the labor of the collectivity with no regard for their personal welfare; so that even violence could be legitimately exercised to dragoon the recalcitrant against their wills. In the Communistic commonwealth morality and law would be nothing but a derivation of the existing economic order, purely earthly in origin and unstable in character. In a word. the Communists claim to inaugurate a new era and a new civilization which is the result of blind evolutionary forces culminating in a humanity without God.

.14. Such, Venerable Brethren, is the new gospel which bolshevistic and atheistic Communism offers the world as the glad tidings of deliverance and salvation! It is a system full of errors and sophisms. It is in opposition both to reason and to Divine Revelation. It subverts the social order, because it means the destruction of its foundations; because it ignores the true origin and purpose of the State; because it denies the rights, dignity and liberty of human personality.

Now, you assert that the motivation was hatred and that this was enough to have nations go to war. The Catholic Church did not advocate war as the remedy for communism (or hatred, for that matter). There is a call for a crusade in Divini Redemptoris, but it is a call for a crusade of prayer--not violence--and it is to be especially undertaken by contemplative orders--not soldiers.

the evil which today torments humanity can be conquered only by a world-wide crusade of prayer and penance. We ask especially the Contemplative Orders, men and women, to redouble their prayers and sacrifices to obtain from heaven efficacious aid for the Church in the present struggle. (Divini Redemptoris, 59)

A theme that runs through Divini Redemptoris is that adherents to communism have been deceived (there are 9 mentions of deception in the text, while there are 0 in Mit Brennender Sorge, an encyclical on fascism published the same month as Divini Redemptoris). We can conclude a number of things from this. In Catholic teaching, being deceived into doing something reduces one's culpability for their actions. Also, the remedy for deception is education--not violence. And this remedy is a positive duty for adherents to Catholicism.

Consider this passage from Pius XII's message to Franco when the Spanish Civil War came to an end:

It falls upon You, Venerable Brothers in the Episcopate, to advise all, so that in their policy of pacification all will follow the principles taught by the Church, and proclaimed with such nobility by the Generalísimo: of justice for crime, and of lenient generosity for the mistaken. Our solicitude, also as a Father, cannot forget these deceived ones, whom a deceitful and perverse propaganda succeeded in enticing with praises and promises. Your Pastoral solicitude should be targeted at them, with patience and meekness: pray for them, seek them, lead them again to the regenerative bosom of the Church and to the warmth of the Fatherland, and lead them to the Merciful Father, Who awaits them with open arms.

That's not a call for vengeance, it's a recognition that there should be justice for crimes but also a demand for mercy and education because these people were "deceived."

So, while the Catholic Church provided ideological opposition to communism dating back to the 19th century, it did not advocate war as the solution. If you look through the encyclicals linked above you will find many critiques of unfettered capitalism as well. The Church did not reject capitalism nearly as harshly as it did communism, but it also recognized that there were many issues within capitalism that it considered to be dangerous or harmful. The solutions to these problems varied somewhat over time, but in general the Church's preferred economic system is known as "distributism." I am less of an expert on this than some, but Wikipedia's entry on the subject is pretty good.

The Catholic Church was just one source of opposition to communism, but it held a consistent position and has done so since at least 1891 with Leo XIII's Rerum Novarum.