Are demons and fallen angels the same thing?
The Bible clearly speaks of demons or evil spirits, but what are they? Are demons fallen angels?
Perhaps the clearest answer can be found in Revelation 12:9: "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.
Another helpful passage is found in Matthew 25:41. Jesus teaches, "Depart from me, you cursed, into the eternal fire prepared for the devil and his angels." Those with the devil are called angels, the same beings called demons or evil spirits in other passages. Therefore, we can conclude demons are fallen angels.
When did these angels "fall"? The timing of their fall is not made exactly clear in the Bible. However, some indications are given. For example, Satan appears in the form of a serpent to Eve in Genesis 3. Since demons are fallen angels who joined Satan when he rebelled, they must have fallen prior to the events in Genesis 3. Isaiah 14 and Ezekiel 28 also mention Satan's fall as a past event.
In fact, it is most likely that this fall occurred shortly before the temptation in the Garden of Eden. Satan would have wasted little time after leaving God's presence to tempt those made in God's image. The best answer is that some 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.
During the time of Jesus on earth, much activity took place by demons. Still today, many reports are made of activities by evil spirits. Ephesians 6:12 clearly teaches our battle is against spiritual forces of evil in the heavenly realms. 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.