One of the problems with this statement is...
Matt 24:21; for then shall be great tribulation, such as has not been since the beginning of the world to this time; no, nor ever shall be.
There have been many times in the world when tribulation was much worse than it is right now. So we definitely are not in the great tribulation.
Also the man of perdition (the beast) will be revealed before the tribulation starts.
2 Thes 2:3; Let no one in any way deceive you, for it will not come unless the apostasy comes first, and the man of lawlessness is revealed, the son of destruction,
I do not have the power to help you understand what I am sharing here and so I can only hope Jesus will help you to understand even if you do not agree with it, but there are 2 events being spoken of in that chapter.
2 Thessalonians 2:1Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto him,
I read the coming of our Lord Jesus Christ as the one event that occurs at the end of the great tribulation, but our gathering unto Him as happening before the great tribulation.
2 That ye be not soon shaken in mind, or be troubled, neither by spirit, nor by word, nor by letter as from us, as that the day of Christ is at hand. 3 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; 4 Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.
So the day of the Bridegroom coming is signaled by the falling away of the faith which is to happen first for why God is judging His House first BEFORE the event of the man of sin will be revealed which will happen after the Bridegroom's visit..
5 Remember ye not, that, when I was yet with you, I told you these things? 6 And now ye know what withholdeth that he might be revealed in his time.
Verse 6 is to dignify that the man of sin will be revealed in his time as happening during the great tribulation; which is halfway though it as per the Biblical timeline. That great tribulation does not start when the man of sin reveals himself, but it starts when the order is given out to build the third Temple. So one has to take everything into account Biblically of what is being meant in His words.
Then I see the reference to the time before that great tribulation as the cause of the falling away of the faith was already at work in Paul's days.
7 For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way.
I see His words applying to that new age mentality that has infiltrated the churches in seeking to receive the Holy Spirit apart from salvation after a sign, even by the sign of tongues that comes with no interpretation. Then Paul switched from the tribulation of our days as it was happening even in Paul's days, ( but more so now ) to the time of the great tribulation when Jesus Christ as the king of kings will deal with that man of sin at the end of the great tribulation in verse 8.
8 And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming:
Then Paul goes back to why God is judging His House first in verse 9-12 again before that event when He comes back as King of kings to judge the world.
9 Even him, whose coming is after the working of Satan with all power and signs and lying wonders, 10 And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved. 11 And for this cause God shall send them strong delusion, that they should believe a lie: 12 That they all might be damned who believed not the truth, but had pleasure in unrighteousness.
So there are 2 events that the Lord will deal with at 2 different times: as the Bridegroom in judging His House first because of the falling away from the faith ( 1 Timothy 4:1-2 ) and then as the King of kings in dealing with the world's armies marching against Jerusalem and defeating Satan to put in the pit for a thousand years.
Paul addresses and reproves the iniquity of our time in this tribulation we are living in now by reminding believers of the ONLY time a believer will receive the promise of the Holy Spirit which is at the calling of the gospel and no other time.
13 But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth: 14 Whereunto he called you by our gospel, to the obtaining of the glory of our Lord Jesus Christ. 15 Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.
Paul goes on to address those falling away from the faith in the very next chapter as wicked and unreasonable men that have not faith that do not follow after the traditions taught of us and are disorderly as those "movements of the 'spirit' " are where saved believers are falling down, speaking in tongues without interpretation and thus assuming it is for private use, and other signs of confusion. That new age mentality is believing one can receive the Holy Spirit again and again and again, and God will permit that strong delusion for believing that lie for why the restraining power of the Holy Spirit is taken out of the way. ( Do note that the Holy Spirit is still in them as He is their seal of adoption as per Ephesians 4:30.) Paul points out in 2 Thessalonians 3:14-15 that we are commanded to withdraw from those that have gone astray, but not to treat them as the enemy, but to admonish them as brothers because they are still His, having His seal. That is why God is judging His House first for why many saved believers will find themselves left behind at the pre great trib rapture event BUT Jesus is faithful in doing a good job in keeping their souls while they suffer being left behind as 1 Peter 4"17-19 in the KJV maintains that message that other modern Bibles do not.
If you do not believe my application to be true, which is understandable, you have to weigh in what Paul was saying about the iniquity that will cause the falling away from the faith as it was happening back in his days so that is evidence of him going back and forth in talking about 2 events. The mistake is believing that the great tribulation starts when that man of sin is revealed, but not so, when the order is given for the third Temple to be built. So Paul's reference to that man of sin being revealed happens halfway thru that great tribulation. His reference to that time of that man of sin is just a reference to the great tribulation period in general, not meaning to say that is when it actually starts.
So we are living in the tribulation of these latter days before the Bridegroom comes to judge His House first for why saved believers still found in unrepentant iniquity shall become castaways to be received later on as vessels unto dishonor in His House at the end of the great tribulation in serving the King of kings for the millennium reign of Christ on earth.
