Second Thessalonians is a followup epistle to the church at Thessalonika, where Paul lays out some more eschatology to Christians who were worried they missed the Second Coming of Christ. Paul assures them the Day of the Lord will not come until there’s a general apostasy that overtakes the whole church, followed by the appearance of the Antichrist who will claim to be the incarnation of God and sit in the Temple, of which, at the time of Paul’s death in 67 CE, still stood intact on Mt. Zion.
This letter therefore presents a problem to modern Christians, because thanks to Romans like Titus and Vespasian there is no more Temple in Jerusalem, and there won’t be another Temple unless the Jews can get the Muslims to move their nice Dome of the Rock mosque off the place where the Holy of Holies used to go. Every time the Jews ask them to do so, the Muslims always say no. The problem hinges on the fact that Christ said he could return at any moment without warning, like a thief in the night. As long as there is no temple, then the thief is kept at bay.
There are Bible Colleges where people spend years of their life figuring all this stuff out. The solution they found was to preserve Immanence with a secret Rapture of True Believers, wherein Jesus comes like a thief in the night and beams up everyone who believes in the Rapture. All atheists and even believers like Roman Catholics who believe in the risen Christ but do not believe in the Rapture will get Left Behind to suffer seven years of wrath from God. It is during the first half of that seven year period that the Temple will be rebuilt and the second half when the Antichrist takes over. Why seven years? Because Daniel mentions a prophetic “week”. Why do Christians get raptured out? Because Romans chapter 8 says there is no condemnation for those who are in Christ Jesus. And so on.
The entire rickety house of cards was built to preserve the Innerancy of Scripture, and it almost works. The one fatal flaw in Rapture theory is that a restored temple would require a revival of the system of animal sacrifices that was set aside when Christ offered himself, once and for all, as the perfect final sacrifice. After all, how could the Antichrist desecrate that which was not sanctified in the first place?