At what point should we consider a belief in demons as a mental condition?

I have known too many people devastated by the concept of demons, fear that they're hiding around every corner, and the misery that comes with their own family telling them that they allowed the demons in to cause their problems.

Answering your title question only, belief that demons exist is nothing to do with a mental condition. All Christians believe that demons exist.

As is the case with any other beliefs, you should seek psychological counseling when the activities of daily life become difficult to perform. Eating, sleeping, going to school, etc. difficulties are the warning signs.

Andrea Yates, Dena Schlosser are two examples of what is wrong with christian crazies.....

drown your kids, hack your infants arms off.... it's all the same

You probably believe in demons too

at the point in which their belief starts being text book...somewhere before they start killing the "demons"

Never. Lack of understanding should not govern your prejudices. Be informed of what you speak of then comment.

We should always see it as a mental disorder. As there is no such thing as demons.