If the forces of light are angels, what are the forces of darkness? Where do they come from? Led by the Devil, they were originally good angels who rebelled and turned against God. These ‘fallen angels’ are also called evil spirits, unclean spirits, or demons. When God created angels they were good so how can they sin? What kind of sin can they commit? ‘Fallen angels’ examines the concept of demons and the Devil in religious thought. It relates these to contemporary culture. The idea of good versus evil has always been popular in literature and film.