Religious experience is conditioned by religious belief, a Catholic's experiences will be defined in alignment with Catholic beliefs. Satan, demons, demonic possession, evil spirits are pure fantasy.
A person acting out according to their ingrained religious beliefs needs the care of a trained doctor, not more indoctrination, however an exorcism may work as a form of extreme role-playing and the placebo effect. Both the exorcist and the person suffering an imaginary possession are both equal victims.
Madness in, madness out.
The religious who believe in satan and demons have a gullible, childish mentality. If one can believe in a literal Genesis, with a talking snake, and a global flood killing humanity, then believing in satan is not difficult for them.
