Demons are fallen angels, as Revelation 12:9 indicates: "The great dragon was hurled down—that ancient serpent called the devil, or Satan, who leads the whole world astray. He was hurled to the earth, and his angels with him.” Satan’s fall from heaven is symbolically described in Isaiah 14:12–15 and Ezekiel 28:12–15. When he fell, Satan took some of the angels with him—one third of them, according to Revelation 12:4. Jude 6 also mentions angels who sinned. So, biblically, demons are fallen angels who, along with Satan, chose to rebel against God.
