25 We know that, by a lamentable abuse of his reason, and still more so of his will, the atheist denies these principles. But, in a word, atheism is so monstrous an error that it could never, be it said to the honor of humanity, annihilate in it the consciousness of God's claims and substitute them with idolatry of the State.
Source: Au Milieu Des Sollicitudes (Vatican.va)