One of the craziest courses I took in college focused a lot on modern day exorcism in the Catholic church. I'm disassociated from the Catholic Church these days, but at least in the mid-2000s, the Church really wanted to avoid the association with exorcism but it was still a technical part of the theology, and most/all diocese had a priest whose duties included being the diocean exorcist, even if he never participates in one. In the process, they also heavily refer potential victims of possession to psychological services, and usually don't even consider one unless -- according to the host or some other loved one -- all other avenues ... psychological treatment, medical treatment, etc, have been exhausted. This is somethign that the movie, The Exorcist, actually does pretty well. The first 30+ minutes are of Reagan getting all sorts of medical treatment from well-to-do doctors and the medical establishment. And finally like ... they're all out of ideas, oh, it's a demon who is targeting the priest all along.
What the hell is extreme knowledge?
"Yo this guy is smart as fuck. Must be demons."
Knowledge of things that somebody should just not have that sort of knowledge of.
There's this book I read when I was really into this stuff, Hostage to the Devil, which is sensationalistic anecdotes of actual exorcism processes, written by an ex-Catholic priest who dropped out of the Catholic Church because he thought the church was
too liberal, and so take what he wrote as fiction or whatever, but one of the anecdotes of transcripts from an exorcism was a young person who knew intimate details of an elderly priest's life from when the priest grew up in Ireland many decades earlier. As an atheist skeptic I don't believe in any of it, but think of it the same way of aliens or ghost stories, and at least from the perspective of the book, that's "extreme knowledge."
I don't believe in god, or many of the beliefs that follow from that, but I also think the brain and perhaps all of our brains together, are weird complex organs that exhibit phenomenon that we've never been able to explain with contemporary understanding of the brain.