same filter
We have to treat everyone equally. There are a lot of people here -- including me -- who have never heard of the Devil before coming here. Your angels sound a hell of a lot like demons where I come from, and I still have to treat Castiel like a person despite my natural inclination to destroy him on principle.
We can't stop people from making dumb choices. If they want to invite Lucifer to possess them and they file a statement with the police saying it's consensual, I can't stop it. I can strongly suggest nobody do that, because it's stupid, but you can't actually regulate stupid.