Are demons fallen angels?

When exactly God created angels is open for debate, but what is known for sure is that God created everything good (Genesis 1:31). God, in His holiness, cannot create something sinful. So, when Satan, who was once the angel Lucifer, rebelled against God, he lost his position in heaven (Isaiah 14; Ezekiel 28). One third of the angelic host joined his insurrection (Revelation 12:3–4, 9). It is likely that these fallen angels are now known as the demons.

Hell was prepared for the devil and his angels, according to Matthew 25:41: “Then [the Lord] will say to those on his left, ‘Depart from me, you who are cursed, into the eternal fire prepared for the devil and his angels.’” The possessive pronoun his indicates that these angels belong to Satan. Revelation 12:7–9 describes an end-times angelic battle between Michael and “his angels” and the devil and “his angels.” From these and similar verses, it seems that demons and fallen angels are synonymous.

Some reject the idea that the demons are the fallen angels, citing Jude 1:6, which says the angels who sinned are “bound with everlasting chains.” However, not all of the sinful angels are bound, as Satan is still free (1 Peter 5:8). Why would God imprison all the fallen angels except for the leader of the rebellion? It seems likely that the confined angels took part in a more heinous rebellion—likely the “sons of God” incident in Genesis chapter 6.

An alternate explanation for the origin of the demons is that they are the spirits of the Nephilim destroyed in the flood (Genesis 6). According to this view, the unclean spirits who repeatedly confronted Jesus (e.g., Mark 3:11, ESV) were the disembodied souls of half-human, half-angelic beings who lived before the flood. The Bible does not say what happened to the souls of the Nephilim when the flood swept them away, so it’s possible that they were allowed to remain on earth in an incorporeal state. We believe the most biblically consistent explanation for the origin of the demons is that they are the fallen angels who continue their satanic rebellion against God.