It is to believed because it is absurd.

It is a fundamental human right, a privilege of nature, that every man should worship according to his own convictions.

But all the other frenzies of passions-impious both toward the bodies and toward the sexes-beyond the laws of nature, we banish not only from the threshold, but from all shelter of the Church, because they are not sins, but monstrosities.

A holy woman may be beautiful by the gift of nature, but she must not give occasion to lust. If beauty be hers, so far from setting it off she ought rather to obscure it.

Woman, thou shouldst ever be clothed in rags and in mourning, appearing only as a penitent, drowned in tears, and expiating thus the sin of having caused the fall of the human race. Woman thou art the gate of the devil. It is thou who hast corrupted those whom Satan dare not attack face to face.

In pain shall you bring forth children, woman, and you shall turn to your husband and he shall rule over you. And do you not know that you are Eve? God's sentence hangs still over all your sex and His punishment weighs down upon you. You are the devil's gateway; you are she who first violated the forbidden tree and broke the law of God. It was you who coaxed your way around him whom the devil had not the force to attack. With what ease you shattered that image of God: Man! Because of the death you merited, even the Son of God had to die... Woman, you are the gate to hell.

I believe BECAUSE it's impossible.