Demons, demons everywhere but nary a drop to drink
My cousin has Schizophrenia. He has been in and out of hospital these last few years, and when he is off his medication he can be violent, particularly towards his mother. His parents are fundamentalist christians. They don't beleive in Schizophrenia, they believe in demons, so he's not sick, nooooooo he's full of demons. Obviously they don't believe what the doctors tell them, so medication is not so important - he needs prayer they reckon.
Bloody hell, he may need prayer but give the boy his fricken meds as well.
Mental illness is such anguish for all involved without adding the warped metaphysical spectre of demons to the story. Are you really sure that you want a person who hears voices believing that he is chock full of evil nasties? That is the shortest route to self harm I have ever heard.