58 See to it, Venerable Brethren, that the Faithful do not allow themselves to be deceived! Communism is intrinsically wrong, and no one who would save Christian civilization may collaborate with it in any undertaking whatsoever. Those who permit themselves to be deceived into lending their aid towards the triumph of Communism in their own country, will be the first to fall victims of their error. And the greater the antiquity and grandeur of the Christian civilization in the regions where Communism successfully penetrates, so much more devastating will be the hatred displayed by the godless.
Source: Divini Redemptoris (Vatican.va)