the thing about this question is that it's not catholicism itself that is horny, it's the perversion of doctrine that provokes the horn, ja feel? like. walk with me:

it's not a priest that makes catholicism horny, it's the fact there is a person who has made a commitment and devotion to serving their community as a vessel for the teachings of jesus, and there is a wide assumption that priests being sexually active and having a wife and children to come home, they must declare celibacy in order to serve their clerical duties without distraction. the temptation being accepted or forced upon them is delicious.

plus, like, the belief in demonic energy, while entirely terrifying...that aligns well with the whole thin line between fear/arousal and all that.

people love to make uniforms horny, too. there is something about someone having their identifiable occupation that becomes a fetish for people. i don't think that's remotely the horniest thing there is to it.

idk. doing something you shouldn't always feels naughty, it's just catholicism has some fucking gorge aesthetics and symbolism and whatnot to incorporate into a horny situation.