When you place 1 Thess: 4 side by side with 2 Thess: 2. 2. they are clearly different events.
Paul is teaching the same exact event in 1 Thessalonians 4:13-5:4 and
2 Thessalonians 2:1-12.
Both of these passages contextually pertain to
the coming of the Lord. The coming of the Lord is the Day of the Lord; the Day of Christ.
For this we say to you by the word of the Lord, that
we who are alive and remain until the coming of the Lord will by no means precede those who are asleep. For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord. Therefore comfort one another with these words. But concerning the times and the seasons, brethren, you have no need that I should write to you. For you yourselves know perfectly
that the day of the Lord so comes as a thief in the night. For when they say, “Peace and safety!” then sudden destruction comes upon them, as labor pains upon a pregnant woman. And they shall not escape. But you, brethren, are not in darkness, so that this Day should overtake you as a thief. 1 Thessalonians 4:15-5:4
Now, brethren, concerning
the coming of our Lord Jesus Christ and our gathering together to Him, we ask you, not to be soon shaken in mind or troubled, either by spirit or by word or by letter, as if from us, as though
the day of Christ had come. Let no one deceive you by any means; for that Day will not come unless the falling away comes first, and the man of sin is revealed, 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.
Do you not remember that when I was still with you I told you these things? And now you know what is restraining, that he may be revealed in his own time. For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way. And then the lawless one will be revealed, whom the Lord will consume with the breath of His mouth and
destroy with the brightness of His coming. 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, that they all may be condemned who did not believe the truth but had pleasure in unrighteousness. 2 Thessalonians 2:1-12
JPT