I wanted to make it clear that the comment about the demons as "an alien race" is not meant literally, but is only used as an example of a way to view their influence on mankind. Demons are fallen angels. They are usually invisible, so therefore they are not easily discernible by people, and because of this they have gotten away with greatly influencing people's thoughts and actions. Their intent has been evil, and they have caused great harm in the earth, without the realization of those who were directly influenced by their presence and actions.
