re: I Will Attempt to Give Y'all an Understanding of Magic

Body Thetans? No such thing, near as I can tell.

I think people got confused by the phenomenon of channeling and convinced themselves that we are surrounded, and indeed even composed of, separate and distinct personalities at all times.

This form of schizophrenia I mentioned in my OP, would be where a person has unknowingly opened lines of communication for disembodied spirits to use their body as a conduit without any means of cutting the spirits off.

In this case, summoning rites worked in reverse may help alleviate such symptoms.

(Disclaimer: please do not attempt anything you read in this thread without careful consideration and maybe guidance from someone with considerable experience. Tinkering with these things can cause permanent mental illness if not done properly)