"Don't let anyone deceive you in any way, for that day will not come until the rebellion occurs and the man of lawlessness is revealed, the man doomed to destruction. He will oppose and will exalt himself over everything that is called God or is worshipped, so that he sets himself up in God's temple, proclaiming himself to be God" (2 Thessalonians 2:3-4).
2 Corinthians is often seen by Christians as referring to the final antichrist -- sometimes referred to as "the Antichrist." Many believe this man will be a future world leader who will rule just prior to Christ's return. Others believe the prophecies concerning the antichrist were fulfilled in the first century. Still others believe the antichrist is a political system rather than a specific person. This is not an essential of the faith, and thus is not an issue to divide over.
The word antichrist can refer to one who is against Christ, or to one who is a counterfeit Christ. The Bible indicates that many antichrists have already come into the world: "Dear children, this is the last hour; and as you have heard that the antichrist is coming, even now many antichrists have come" (1 John 2:18).
Those who believe the final antichrist has not yet come believe he will reign during the future Tribulation period. They view the Tribulation as a time of unprecedented terror. This antichrist is called the "beast," and his reign is described in Revelation 13: "The beast was given a mouth to utter proud words and blasphemies and to exercise his authority for forty-two months...He was given power to make war against the saints and to conquer them. He was given authority over every tribe, people language and nation .... He also forced everyone ... to receive a mark on his right hand or on his forehead, so that no one could buy or sell unless he had the mark" (Revelation 13:5, 7, 16-17).
The antichrist will persecute the Tribulation saints, and many will be put to death rather than receive the mark. His reign will end at Christ's second coming: "Then I saw the beast and the kings of the earth and their armies gathered together to make war against the rider on the horse and his army. But the beast was captured, and with him the false prophet who had performed miraculous signs on his behalf. With these signs he had deluded those who had received the mark of the beast and worshipped his image. The two of them were thrown alive into the fiery lake of burning sulfur" (Revelation 19:19-20).