Question: "Is the war in heaven in Revelation 12 describing Satan's original fall or an end times angelic battle?"
Answer: The last great angelic battle and Satan’s ultimate expulsion from heaven is described in Revelation 12:7-12. In this passage, John sees a great war between Michael and the angels of God and the dragon (Satan) and his fallen angels or demons that will take place in the end times. Satan, in his great pride and delusion that he can be like God, will lead a final rebellion against God. It will be a cosmic mismatch. Thus, the dragon and his demons will lose the battle and be thrown out of Heaven forever.
A common misconception is that Satan and his demons were locked away in hell after the fall of Satan. It is clear from many Bible passages that Satan was not barred from heaven or the earth after his first rebellion, which predated the creation. In Job 1:1–2:8, he appears before God to accuse Job of ulterior motives in his worship of God. In Zechariah 3, he again appears before God to accuse Joshua, the High Priest. Indeed, the name Satan means accuser. In Genesis, he visited the Garden of Eden and tempted Eve. He tempted Jesus in the wilderness before Jesus began His ministry, which is recorded in Matthew 4:1-11. The question arises that if Satan had already rebelled and been cast from heaven before the world was created, why is he free to be in heaven and on earth?
In 2 Corinthians 12:2-3, the apostle Paul provides a major revelation that there are three heavens. In this passage, he seemingly talks about himself being taken up to the “third heaven” where God the Father and Jesus dwell. The second heaven is the universe, outer space, and our atmosphere or air. The Bible indicates that Satan and some of his demons are allowed to move in this space (Ephesians 2:1-2, 6:12).
In this age, Satan and his highest ranking angels can still oppose the work of God and hinder the angels of God (Daniel 10:10-14) within the boundaries of the middle or second heaven. The battle recorded in Revelation 12 removes Satan and his minions from this realm.
When Satan is expelled from the middle heaven, there will be great rejoicing in heaven, since the age-old accuser will be forever banned from his mission of accusation and slander against the elect. Satan’s power and freedom will be seriously curtailed. However, the inhabitants of the earth will suffer terribly after this event, because Satan will be enraged. He will also be aware that he only has three and a half more years until he is bound and cast into the bottomless pit. This will usher in a period of intensified suffering on earth (Great Tribulation) during which the Antichrist violates his peace treaty with Israel, desecrates their temple, declares himself as god, and begins to systematically murder all those who refuse to worship him.