In some cultures and religions, demons exist as destructive spirits, causing pain and grief wherever they go. In other cultures and religions, demons do not exist.
In religions and cultures that believe in the existence of demons, religious doctrines contain elements of supreme good and supreme evil, such as demons and devils, which constantly battle for the souls of humans. Demons run rampant, possessing and destroying humans to win souls.
In religions and cultures that do not believe in demons, the widespread belief is that people make their own destinies by the choices they make in life. A run of bad luck is caused by bad choices, not demons.