Demons or Demented?

I'm interested in a lot of things. 
One of those lots of things is mental disorders.  This is probably because so many writers I had to learn about had one.

Mental disorders, really any sickness, used to be thought of as the work of the devil.  And then they thought chemicals in the brain had gone whacko.

I learned in Psychology two semesters ago that not all mental disorders are caused by chemical imbalances.

The human mind is a scary place.  But is it really that scary or is something really whispering in your ear?  Do you have an overactive imagination or is something or someone putting it there?

I think it's creepy either way.

In the cases where people hear voices or have multiple personalities, I can almost believe that demons (or other malevolent beings) are involved.  Believing that they're allowed to mess with our minds so much, I start to doubt this.  I definitely understand why they believed it, though.

Before we knew that there's a billion things going on in our brain, what other explanation was there?  Could you really get sick in the head?

Well, considering the book of Job, maybe it isn't so hard to believe that demons mess with our minds.  Look at what he went through.  Although, none of it was mental, really.  I'm sure it drove him crazy anyway.