In our present volume we review briefly the story of Satan's rebellion and fall. We then consider the Bible evidence concerning the origin of demons and note that they are a part of Satan's kingdom, although they are not to be confused with fallen angels. Demons are disembodied spirits which seek human habitation. On the other hand, fallen angels inhabit the heavenlies and engage in warfare against the angels of God. The latter are the rulers of darkness spoken of by the apostle Paul in Ephesians 6:12.