22 This, unfortunately, is what we now behold. For the first time in history we are witnessing a struggle, cold-blooded in purpose and mapped out to the least detail, between man and "all that is called God." Communism is by its nature anti-religious. It considers religion as "the opiate of the people" because the principles of religion which speak of a life beyond the grave dissuade the proletariat from the dream of a Soviet paradise which is of this world.
Source: Divini Redemptoris (Vatican.va)