Are demons and fallen angels the same thing?

what does the bible say?

Yes, demons are fallen angels. Demons originated as angels who joined Satan in his rebellion against God. Isaiah 14 and Ezekiel 28 describe Satan’s fall, while Revelation 12:9 confirms that he and his angels were cast down to earth. These angels, now referred to as demons or evil spirits in various passages (Mark 1:34; Luke 4:41), have been active since Satan's rebellion, which likely occurred before the creation of humanity. While demonic activity continues, Christians are protected by Christ’s victory over these forces and are secure through faith in God (Colossians 2:15; 1 John 4:4).

from the old testament

Satan appeared in the form of a serpent to Eve in Genesis 3. Since hell was prepared for Satan and his angels, we can posit that demons, or fallen angels, must have fallen prior to the events in Genesis 3.Isaiah 14 and Ezekiel 28 also mention Satan's fall as a past event.Based on the book of Job, Satan’s fall occurred prior to the creation of humanity.Angels became demons, or fallen angels, sometime between God's creation of the heavens and the earth in Genesis 1:1 and the temptation in Genesis 3.

from the new testament

When Jesus was teaching the parable of the sheep and the goats, He said, "Depart from me, you cursed, into the eternal fire prepared for the devil and his angels" (Matthew 25:41). Those with the devil are referred to as angels, the same beings called demons or evil spirits in other passages (Mark 1:34; Luke 4:41). Therefore, we can conclude that demons are fallen angels.Revelation 12:9 says: "And the great dragon was thrown down, that ancient serpent, who is called the devil and Satan, the deceiver of the whole world—he was thrown down to the earth, and his angels were thrown down with him." This verse states Satan is the devil and the serpent from Genesis 3. He was thrown down to earth with his "angels." The evil spirits, or demons, described in the Bible appear to be angels who joined Satan in his rebellion against God. Although it does not explicitly state it, we can conclude reasonably that the demons, or fallen angels, followed Satan when he rebelled, prior to the creation of the world and humanity.

implications for today

During the time of Jesus on earth, much activity took place by demons. Still today, many reports are made of activities by evil spirits. Despite their activity, Christians don't have to fear demons, or fallen angels, because Christ has already triumphed over them through His death and resurrection (Colossians 2:15). Believers are under God's protection, and His Spirit within them is greater than any spiritual force (1 John 4:4). By standing firm in faith and relying on God's power, Christians are secure from the schemes of the enemy (Ephesians 6:10–11).

Demonic spirits will continue to operate during the judgment of the tribulation period as well. However, demonic activity will be defeated at the return of Christ at the Battle of Armageddon (Revelation 19:17–21). After the 1,000-year millennial kingdom, there will be one final battle, at which Christ and those with Him will defeat Satan and those with him for good (Revelation 20). The curse will end, and a new heaven and earth will be created where all of God's people will dwell with Him forever.