Pope Leo XIII condemned communism and socialism, calling them a "pernicious evil that promotes a satanic war against God."
And Pope Pius XI denounced the socialist system as a "threatening danger that seeks to overthrow the Christian social order," one that "rejects the wisdom of the Gospel and revives paganism."
In addition to his blasphemy, Petro made a public declaration of his apostasy. Petro claimed that the false Jesus in whom he believes was not Christ.
Wisdom of Ben Sira 11:16 Error and darkness were created with sinners from their birth, and evil grows old with those who take delight in it.]
Sins against faith:
Apostasy: This is the complete abandonment of the Christian faith received in baptism; for example, Catholics who change religions or those who, without formally changing religions, have completely distanced themselves from the Catholic faith, falling into rationalism, pantheism, Marxism, Freemasonry, etc.
but the mighty will be tested with rigor.
Apostasy from the Faith is defined as “the complete and voluntary abandonment of the Christian religion, whether the apostate embraces another religion such as Paganism, Judaism, Mohammedanism, etc., or merely makes profession of Naturalism, Rationalism, etc.” (Catholic Encyclopedia, s.v. “Apostasy”).
God's curse falls upon the communist apostate Gustavo Petro.
But though we, or an angel from heaven, preach a gospel to you besides that which we have preached to you, let him be anathema.
As we said before, so now I say again: If any one preach to you a gospel, besides that which you have received, let him be anathema.
-Communism is intrinsically wrong and no one may collaborate with it in any undertaking whatsoever
Congregation for the Doctrine of the Faith– Formal prohibition to join or favor Communist Parties – latae sententiae excommunication
Pope John XXIII– No Catholic can subscribe even to moderate Socialism – opposition between Communism and Christianity is fundamental.
Congregation for the Doctrine of the Faith
Formal prohibition to join or favor Communist Parties – latae sententiae excommunication
1. Whether it is lawful to join Communist Parties or to favour them;
2. whether it is lawful to publish, disseminate, or read books, periodicals, newspapers or leaflets which support the teaching or action of Communists, or to write in them;
3. whether the faithful who knowingly and freely perform the acts specified in questions 1 and 2 may be admitted to the Sacraments;
4. whether the faithful who profess the materialistic and anti-Christian doctrine of the Communists, and particularly those who defend or propagate this doctrine, contract ipso facto excommunication specially reserved to the Apostolic See as apostates from the Catholic faith.
To 1. in the negative: because Communism is materialistic and anti-Christian; and the leaders of the Communists, although they sometimes profess in words that they do not oppose religion, do in fact show themselves, both in their teaching and in their actions, to be the enemies of God, of the true religion and of the Church of Christ;
to 2. in the negative: they are prohibited ipso iure (cf. Can. 1399 of the Codex Iuris Canonici);
to 3. in the negative, in accordance with the ordinary principles concerning the refusal of the Sacraments to those who are not disposed;
to 4. in the affirmative. (Replies confirmed by Pius XII on June 30) (Denzinger-Hünermann 3865. Decree of the Holy Office, July 1, 1949)


