In his letter to the Thessalonians, speaking about the return of Jesus Christ to the earth, he writes, “Let no one deceive you by any means; for that Day will not come unless the falling away comes first” (2 Thessalonians 2:3 2 Thessalonians 2:3Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
American King James Version×). He then proceeds to explain this “falling away” or apostasy from the truth in greater detail.
Paul writes that it will involve the revealing of “the man of sin . . . the son of perdition, who opposes and exalts himself above all that is called God or that is worshiped, so that he sits as God in the temple of God, showing himself that he is God” (2 Thessalonians 2:3-4 2 Thessalonians 2:3-4  Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
 Who opposes and exalts himself above all that is called God, or that is worshipped; so that he as God sits in the temple of God, showing himself that he is God.
American King James Version×). Some man is going to put himself in the place of God, effectively claiming to be God—and people will believe him. Why? Because: “The coming of the lawless one is according to the working of Satan, with all power, signs, and lying wonders, and with all unrighteous deception among those who perish, because they did not receive the love of the truth, that they might be saved. And for this reason God will send them strong delusion, that they should believe the lie” (2 Thessalonians 2:9-11 2 Thessalonians 2:9-11  Even him, whose coming is after the working of Satan with all power and signs and lying wonders,  And with all delusion of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved.  And for this cause God shall send them strong delusion, that they should believe a lie:
American King James Version×).
The “man of sin,” posing as divine, will be performing supernatural acts with the help of the devil, deceiving all those who have rejected God and setting himself up to be worshipped by the world.
Revelation 19:20 Revelation 19:20And the beast was taken, and with him the false prophet that worked miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone.
American King James Version×describes this powerful religious leader as “the false prophet who worked signs” in connection with the political leader called the “beast.” The False Prophet is the same as the one called “another beast” in Revelation 13:11 Revelation 13:11And I beheld another beast coming up out of the earth; and he had two horns like a lamb, and he spoke as a dragon.
American King James Version×, who performs miraculous “signs” (Revelation 13:14-15 Revelation 13:14-15  And deceives them that dwell on the earth by the means of those miracles which he had power to do in the sight of the beast; saying to them that dwell on the earth, that they should make an image to the beast, which had the wound by a sword, and did live.  And he had power to give life to the image of the beast, that the image of the beast should both speak, and cause that as many as would not worship the image of the beast should be killed.
American King James Version×). He is also the leader of the false church (“the harlot”) in Revelation 17:1-5 Revelation 17:1-5  And there came one of the seven angels which had the seven vials, and talked with me, saying to me, Come here; I will show to you the judgment of the great whore that sits on many waters:  With whom the kings of the earth have committed fornication, and the inhabitants of the earth have been made drunk with the wine of her fornication.  So he carried me away in the spirit into the wilderness: and I saw a woman sit on a scarlet colored beast, full of names of blasphemy, having seven heads and ten horns.  And the woman was arrayed in purple and scarlet color, and decked with gold and precious stones and pearls, having a golden cup in her hand full of abominations and filthiness of her fornication:  And on her forehead was a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF HARLOTS AND ABOMINATIONS OF THE EARTH.
American King James Version×. He is also referred to as “another horn” who will “persecute the saints of the Most High, and shall intend to change times and law” in Daniel 7:8 Daniel 7:8I considered the horns, and, behold, there came up among them another little horn, before whom there were three of the first horns plucked up by the roots: and, behold, in this horn were eyes like the eyes of man, and a mouth speaking great things.
American King James Version×, Daniel 7:20-22 Daniel 7:20-22  And of the ten horns that were in his head, and of the other which came up, and before whom three fell; even of that horn that had eyes, and a mouth that spoke very great things, whose look was more stout than his fellows.  I beheld, and the same horn made war with the saints, and prevailed against them;  Until the Ancient of days came, and judgment was given to the saints of the most High; and the time came that the saints possessed the kingdom.
American King James Version×, Daniel 7:24-25 Daniel 7:24-25  And the ten horns out of this kingdom are ten kings that shall arise: and another shall rise after them; and he shall be diverse from the first, and he shall subdue three kings.  And he shall speak great words against the most High, and shall wear out the saints of the most High, and think to change times and laws: and they shall be given into his hand until a time and times and the dividing of time.
American King James Version×.
What should you do? We’re told there’s one thing that can save you from being deceived: Have the love of the truth. That means knowing the Bible, understanding what it says and obeying the law of God out of love. If you’re going to avoid being deceived by this man of sin, you’d better know the law—and do it!