A demon is a supernatural immortal creature which is an enemy of God and totally evil. Demons may also be referred to as 'devils,' with a lowercase initial letter to differentiate them from the Devil, a title for Satan. A succubus is an example of one kind of demon.
Putting on the "Armor of God," Ephesians 6:10-20, is the response in Scriptures. Ephesians 6:11 states, “Put on the whole armor of God, that you may be able to stand against the schemes of the devil.”[1]
In the Old Testament, God uses 'evil spirits' to serve His purposes. The precise nature of these spirits is unclear, but they may be classed as demons.
In the New Testament, Jesus cures the illnesses of various people by casting possessing demons from them.
Demons, and 'evil' or 'unclean' spirits are mentioned at least fifty times in the new testament.
More liberal-leaning Protestants tend to either ignore or explicitly reject the existence of demons, or view scriptural passages about them as metaphorical for sin or illness. The Catholic Church still acknowledges that demons exist and actively try to corrupt humans into sinful behavior, but has reduced the significance of this element of doctrine.
More conservative Protestants, especially those from evangelical denominations, see demons as engaging in a constant struggle for the soul of each person. Fallen angels who followed Satan in his rebellion, demons are believed to operate in secret in order to corrupt and influence individual humans in order to ensure they turn away from Christ. For some examples of this, see the works of Jack Chick.
Jehovah's Witnesses believe that Demons are Rebel Angels that willfully left their heavenly dwelling places, and abandoned their assigned tasks given to them by Jehovah God, their Father (Genesis 6:2) (Jude 1:6).[2] They believe that at some point before the flood they came to Earth, materialized bodies and took Human wives for themselves. They believe that these Angels then fathered children, called Nephilim, with these Human wives and that their children were hybrid, giants that dominated Human society and filled the Earth with violence, threatening Jehovah's Purpose for the Earth to be filled with Adam's offspring (Genesis 6:4-7).[3]
Jehovah's Witnesses teach that God flooded the world in Noah's day, and that these Angels simply dematerialized and went back to Heaven, but were unable to bring their Nephilim offspring or Human wives with them. Having left their original positions in Heaven, Jehovah's Witnesses believe that they in effect Joined Satan's rebellion and are now under Satan's authority unable to regain their prior positions (Jude 1:6).
Jehovah's Witnesses believe that Satan and the Demons ruled the Earth from somewhere in Heaven until The Kingdom of God began to rule (ephesians 6:12) in the year 1914 C.E.[4] At this time, Witnesses teach that Jesus Christ (Michael the Archangel) led the Armies of Heaven against Satan and his rebel Angels and hurled them to the Earth where they remain to this day (Revelation 12:7-8).[5] They do not believe that Satan and his Demons live in any sort of underworld or Hell, or that they have anything to do with punishing wicked people (Ezekiel 18:4) (Romans 12:19).[6]
Jehovah's Witnesses believe that Satan has ruled the world since the rebellion in Eden, and that he now delegates authority to the Demons over the Earth. The belive that these invisible rulers are Evil. They teach that different Demons rule different Nations and Organizations on Earth and control them by means of spiritual inspiration (Daniel 10:13,20).[7][8] They teach that the Kingdom of God will remove all Human governments/kingdoms, and destroy Satan and all of the Demons forever. They do not believe that these Demons are immortal, but that they can and will eventually die for their Rebellion.[9]
Demons are, by definition, evil. This moral unambiguity makes them useful antagonists in TV series such as Charmed, as the 'good guys' can kill demons without either moral dilemma or proof of guilt for any specific crime. They also play important parts in Frank E. Peretti's novels, such as This Present Darkness and The Visitation. Other works of fiction, including Buffy the Vampire Slayer, Angel, and many comic series, depict demons who, possessing free will, can choose to do good.