A demon is a fallen angel. When Satan, who was the very highest angel, rebelled against God, he took a large number of the angels with him in rebellion. When their rebellion failed, they were cast out of heaven. Those angels are now demons. (see Isaiah 14:12-15, Ezekiel 28:12-19, Luke 10:18, Revelation 12:3-9, Matthew 12:43, 45, Matthew 25:41, II Peter 2:4, Ephesians 6:12, Jude 6). In the same way that angels can reach the very heights of spirituality, demons have the ability to reach down into great depths of hatred, bitterness, and perversion. Demons seem to be interested in tormenting people, possessing them, and leading them away from God and His truth.
Although lust, homosexuality, drunkenness, gluttony, and witchcraft are expressions of sinful flesh, these things can also be expressions of demonic activity in the lives of people. I am persuaded that many grossly perverted sexual practices, such as sadomasochism and pedophilia (sexual preference for children), have demonic roots. In a similar manner, schizophrenia (split personality) can be a mental disease, but it can also be caused by demon possession. I believe that Adolf Hitler and Karl Marx were both demonized.
Just as the angels have archangels and higher powers, the demons have what are called “principalities and powers.” It is possible that a demon prince is in charge of New York, Detroit, St Louis, or any other city. Particular sins are prevalent in certain cities. One city might have rampant homosexuality, while another might be troubled by excessive lust. In another, it may be witchcraft or spiritism. Nations, as well as cities, can be gripped by demon power. This could explain the willingness of the German people to tolerate the attempt of Adolf Hitler and the Nazi SS to exterminate all of the Jews in Europe.
There is conflict in the invisible world between God’s loyal messengers and demonic hosts. Somehow in God’s wonderful order, He uses the prayers of His people to restrain demonic activity and to direct the action of angelic powers to control demons. The book of Daniel tells of a struggle between the archangel Michael and the demonic “Prince of Persia” (see Daniel 10:12-13,20).
The Bible says, “He who is in you is greater than he who is in the world” (I John 4:4). The Christian believer, by having the Holy Spirit within him, has power over all demons. When Jesus Christ sent His apostles out on their mission, He said He was giving them authority (exousia) over all the power (dunamis) of the enemy. Jesus’ authority is greater than satanic power. When the disciples returned, they told of casting out demons. The Lord said, “Nevertheless do not rejoice in this, that the spirits are subject to you, but rather rejoice because your names are written in heaven” (Luke 10:20). The Christian believer has unlimited authority over demons in the name of Jesus, but that authority is nothing compared to the glory and authority we will know in heaven.