That's assuming the Antichrist has yet to arise, assuming the Antichrist is a single evil person who will arise and sit in a rebuilt temple in Jerusalem, assuming that that rebuilt temple is actually the "temple of God".
Well, the early Church father Irenaeus interpreted that 'man of sin' as sitting in a physical temple in Jerusalem, and he wasn't alone in that understanding. So I guess you disagree with many of the early Church fathers too. No matter, because it is impossible for Paul's "temple of God" to mean anything other than the traditional temple in Jerusalem, since per Ephesians 2 Apostle Paul taught that Christ's spiritual temple is based on a foundation of His prophets and Apostles, with Him as its Chief Cornerstone, which shows the spiritual temple cannot... be corrupted by any man. Anyone who tries to corrupt the spiritual temple is simply cut off from it, as any true Christian should be able to fathom.
Thus understanding Paul was speaking of a literal physical temple in Jerusalem for the end, with that 'man of sin' coming to play God in it, is not an assumption.
Furthermore, I have already covered in previous posts the 1 John 2:18 Scripture where John mentioned both a singular "antichrist", and the idea of the "many antichrists". I even showed how that is the same teaching our Lord Jesus gave in His Olivet discourse when Jesus warned of 'many' coming in His name only saying... they are Christ (Matt.24:4-5), which is John's idea of the "many antichrists". Then later in that same chapter, our Lord Jesus revealed the coming of a singular antichrist working great signs and wonders that if possible would deceive even His very elect. And that is John's idea of the antichrist the brethren had already heard shall come.
In 2 Thess.2, Apostle Paul gave the same info, as he warned of the coming singular antichrist first associated with the falling away event, and then he mentioned the "mystery of iniquity" already being at work, which is John's "many antichrists" already at work.
And here's a little list to make that more plain that all 3 are the same Message...
1 John 2:18-
1. they heard that "antichrist" shall come -- a singular Antichrist
2. "many antichrists" already at work -- Antichrist's servants already at work in the world, i.e., like the tares of Matt.13. Start with Cain, the first murderer; that's how long they've been at work.
Matthew 24 -
1. verses 4-5 - many that come
saying they are Christ. The "many antichrists".
2. verses 23-26 - the singular antichrist coming with supernatural power to deceive the whole world into believing he is Christ.
2 Thessalonians 2-
1. verses 3-4 - the man of sin as a singular antichrist, working signs and lying wonders to deceive the world that he is God.
2. verse 7 - the mystery of iniquity already at work - John's "many antichrists"
However, Paul said there was a "restrainer" preventing the rise of this "man of sin" Antichrist, and when it was "taken out of the way" the Antichrist would arise. Now, you probably think according to your Jesuit "left behind" Futurist ideas that this restrainer is "the Holy Spirit filled church" or some other agent of holiness which will be "taken out of the way" by the "secret rapture", after which this evil Antichrist dude will arise.
There is no such word as "restrainer" in the manuscripts of 2 Thess.2. The idea of restraining as a verb is used in several English translations; the KJV uses the idea of "withholdeth". Certain traditions use that "restrainer" word in their preaching, like those on a Pre-trib Rapture theory. In reality then, you're stance on that terminology as a Futurist.
And no, I do not think The Holy Spirit is the one Paul said is withholding the coming Antichrist. Nor am I a Jesuit, nor a Catholic even, so once again it's your assumptions that are way... off base. I believe in a post-tribulational coming of Lord Jesus and gathering of His Church, as written.
The one who is withholding that Paul spoke of, is most likely Archangel Michael. Per Revelation 12:7 that is who casts Satan and his angels out of the Heavenly down to this earth for the last days. Daniel 12:1 also shows Michael making a stand, and then a time on earth the likes that has never been before, nor ever will happen again, will come, linking to what Jesus warned in Matthew 24 about the time of great tribulation.
Dan 10:20-21
20 Then said he, Knowest thou wherefore I come unto thee? and now will I return to fight with the prince of Persia: and when I am gone forth, lo, the prince of Grecia shall come.
21 But I will shew thee that which is noted in the scripture of truth: and there is none that holdeth with me in these things, but Michael your prince.
KJV
The problem with all that is Paul told the early church the Restrainer was the Roman Empire, and every Early Church Father who had anything to say on this subject understood the Restrainer to be such - not some "agent of holiness" down at the end of time.
I guess you missed my quote from Irenaeus where he spoke of the coming of the Antichrist in the last days to sit in a physical temple in Jerusalem (see
Against Heresies, Book V).