I have been reading Criminal Intent, the story of Aileen Wuornos. As I was viewing some of her stuff on you-tube, I came across Jeffery Dauhmer. His story is so strange because he didn't have the 'history/exuse' that Aileen had, and yet he became so degraded.
When I read stories like this, it absolutely humbles me to the core. It humbles me because of magnatude of evil a human is capable of, and I am human. Therefore I am capable of these things.
I remember reading the story of a nun who was demon-possessed. I believe it started when she started fantasizing sexually about a new priest in the convent, from that point the demon began manifesting. Maybe couldn't identify herself as having those thoughts, thus the manifestation.
I wonder if demons are a manifestation of something within us that we do not identify with because we can not fathom the depths of our own evil hearts. Just a thought.