Question: "What will happen when Jesus returns / comes back?"
Answer: The second coming of Christ is referenced many times in Scripture, with over 1,500 passages in the Old Testament and one out of every 25 verses in the New Testament mentioning the Messiah’s return. The large amount of material devoted to this important event underscores what God says in Amos 3:7: “Surely the Sovereign LORD does nothing without revealing his plan to his servants the prophets.”
In short, the return of Christ brings about what is referred to as the kingdom of God in Scripture—God’s absolute rule over His creation, including humankind. To accomplish that, Jesus ushers in two different judgments, two different resurrections, and two different eternities.
When Jesus returns, He will be ready for war (Revelation 19:11–16). The nations will be gathered to fight against Jerusalem (Zechariah 14:2) in what we call the battle of Armageddon. But that will be the day Jesus returns: “His feet will stand on the Mount of Olives, east of Jerusalem, and the Mount of Olives will be split in two from east to west, forming a great valley, with half of the mountain moving north and half moving south” (verse 4). It will be a unique day in the history of the world: “On that day there will be neither sunlight nor cold, frosty darkness . . . a day known only to the Lord—with no distinction between day and night. When evening comes, there will be light” (verses 6–7). God’s enemies will be defeated, and the Antichrist and the false prophet will be “thrown alive into the fiery lake of burning sulfur” (Revelation 19:20). Jesus will set up His kingdom, and “The Lord will be king over the whole earth” (Zechariah 14:9).
In establishing His kingdom on earth, Jesus will first set up a judgment for those who are still alive after the tribulation and who are on the earth at the time of the second coming. This is referred to as the “judgment of the sheep and the goats” or “judgment of the nations” (Matthew 25:31–46). Those who survive this judgment will remain on earth and enjoy a time of peace and prosperity with Christ for 1,000 years (referred to as the millennium; see Revelation 20:4–6). Those who are found guilty in this judgment are cursed and consigned to “the eternal fire prepared for the devil and his angels” (Matthew 25:41). Satan is bound and forbidden to act during the millennium (Revelation 20:1–3).
During this time there will also be a resurrection of all believers in God (Revelation 20:4–6). These resurrected believers will join believers who are alive at the time of Christ’s coming and those Christ brings with Him from heaven, and all will live with Jesus during His 1,000-year earthly reign.
At the end of the millennium, Satan will be released, and one final battle will occur, which will rapidly be won by Christ (Revelation 20:7–9). Satan is then permanently consigned to the lake of fire. At this point the second resurrection will occur, and another judgment. Unbelievers will be resurrected and judged at what is referred to as the great white throne judgment; based on their works, they will be assigned to the lake of fire (Revelation 20:11–15).
So, the return of Jesus will usher in two different eternities—one with God and one without Him. This truth is captured in two verses in the book of Malachi: “Surely the day is coming; it will burn like a furnace. All the arrogant and every evildoer will be stubble, and the day that is coming will set them on fire. . . . Not a root or a branch will be left to them. But for you who revere my name, the sun of righteousness will rise with healing in its rays. And you will go out and frolic like well-fed calves” (Malachi 4:1–2).
What happens when Jesus returns? Evil is defeated, the earth is restored, and God wins. Your response to Jesus’ return depends on your relationship with Him. It will either be, as John MacArthur calls it, “the greatest calamity in all of human history” or the fulfillment of the Blessed Hope (Titus 2:13). Faith in Christ makes the difference. “But when the Son of Man returns, how many will he find on the earth who have faith?” (Luke 18:8, NLT).