He knows this because he’s an exorcist.
I love your tagline!
No he doesn’t. I agree he knows the worldly manifestations of demons in the material world. He knows more than I ever want to know. :-). But he does not know how demons were created and all the details he wrote about.
“He knows this because he’s an exorcist.”
I don’t mean to sound flippant here. Do the demons talk to him and tell him this stuff? Otherwise, where does he get it? Certainly scripture does not go into nearly this much detail.