If he was a devout Christian and you are a believer in the least, I would say uhm, maybe take him to church?

Definitely had friends do similar tangential things in their lives and sometimes a good sermon can get them back into reality (ironic to most of you redditors, I know).

Honestly, once my friend got so into the dark spirit scene that she invited a demon into her home. He was there for quite some time :-) not a great time really but when she returned to church and what she had known to be true before, it was a helpful and healthy wake up call. Maybe reintroducing him to the truths he lived by before (which directly contradict a lot of this weird behavior???) could be a nonconfrontational way to steer him back to a world of relative sanity.

I totally get it being hard and wanting to support him, so though communication is vital, people often don’t do well to a head on contradiction of their beliefs.