The phenomenon of poltergeists would be the most extreme form of such influence. About the duality between Good and Evil, his philosophy is to live doing good, following the laws of the positive. His concept of God is the creative power of the universe. He dislikes the people who follow the philosophy of black magic. He considers that the biological shaping of such beings can be very different from what we can imagine.
Nightmares are very interesting and with great strength, artistically speaking.
However, I don't so often paint such things, at least for now. Some ten years ago, I did.