Your right, you don't need to be psychotic to wonder this. After all many "normal" people believe in demons too. I think it's a valid point and not delusional unless you really believe your possessed and or they are talking to you. To simply wonder about it is ok. I wonder too! Because every night I am awaken by what feels like some one shaking me or kicking me. I've also often wondered if all mental illness is caused by demons.

I think it gets worse with the paranoia and anxiety. I think we create our own demons.

Best of luck and wishes for you!