Many of the Christians interested in eschatology who post on Christian Forums believe that Paul prophesied that a Man of Sin will desecrate the Temple in Jerusalem. They believe that the Man of Sin, or Man of Lawlessness, will enter the Jewish Temple and proclaim himself to be God. For this prediction to be fulfilled, the Jewish Temple must be rebuilt, so it would seem.
Paul wrote about the Man of Lawlessness, or Man of Sin, in 2 Thessalonians 2: 1-12, and most pointedly in verses 3-4.
3 Don’t let anyone deceive you in any way, for that day will not come until the rebellion occurs and the man of lawlessness[
a] is revealed, the man doomed to destruction.
4 He will oppose and will exalt himself over everything that is called God or is worshiped, so that he sets himself up in God’s temple, proclaiming himself to be God.
2 Thessalonians 2: 3-4 NIV
2 Thessalonians 2:3 a: Some manuscripts
sin [or man of sin]
Paul doesn't say that the Man of Sin will enter the Jewish Temple, or the Temple in Jerusalem. He says that the Man of Sin will set himself up "in God's temple." The NIV, RSV and KJV all agree that the phrase is either "God's temple" or "the temple of God." The question is, is "God's temple" the same as the Jewish temple? A strong case can be made that it is not.
Scholars believe that 1 Thessalonians was most likely written in 51 AD and that 2 Thessalonians was written only a few months later. What this means is that that Temple in Jerusalem was still standing and open for business when both letters were written. At first glance, that might seem to support the notion that Paul was talking about the Temple in Jerusalem. We know that the Roman army tore down the Temple in Jerusalem in 70 AD, only 19 years later. Consider the impact of these letters and later events on the Thessalonians if we assume that the Thessalonians thought that Paul meant the Temple in Jerusalem. First, Paul tells them that at some time in the future, before the Second Coming, a Man of Sin will enter the Jewish Temple and commit sacrilege. Then, before this prophecy is fulfilled, a Roman army tears the Temple down. There is no realistic prospect of it being rebuilt. The Romans will not allow a Jewish Temple to be rebuilt. If the Jews had somehow managed to rebuild the Temple, the Romans would simply tear it down again. The most likely result is that the Thessalonians would lose faith in Paul and in the religion that he taught.
Suppose that Paul did know and understand the future in considerable detail. Suppose that he meant to refer to the Jewish Temple, and he knew that it would be destroyed and not rebuilt for hundreds of years. If these things had to happen before his prophecy was fulfilled, surely he would have said so. Paul would not have imperiled the faith of the Thessalonians by failing to mention that point.
There is another possibility. Paul never meant for "God's Temple" to mean the Temple in Jerusalem. The passage doesn't mention Jerusalem, Israel, Palestine, or Jewish priests. Paul may not have intended "God's Temple" to refer to a physical building at all.
In the second Chapter of Ephesians, Paul refers to a "holy temple" with Jesus Christ as the Cornerstone. This is not the Temple in Jerusalem. It is not the Jewish Temple. The spiritual temple with Jesus as the Cornerstone is the Temple that Paul was talking about in 2 Thessalonians Chapter 2.
19 Consequently, you are no longer foreigners and strangers, but fellow citizens with God’s people and also members of his household,
20 built on the foundation of the apostles and prophets, with
Christ Jesus himself as the chief cornerstone.
21 In him the whole building is joined together and rises to become
a holy temple in the Lord.
22 And in him you too are being built together to become a dwelling in which God lives by his Spirit.
Ephesians 2: 19-22 NIV
What this means is that the Man of Sin is not someone who desecrates the Temple in Jerusalem, should one be standing at the time. The Man of Sin is someone who enters the Christian church, is accepted as a Christian, and then claims a position before God that no mortal can possess. The Man of Sin is not a military leader who takes the temple mount by force and has his own way. Instead, the Man of Sin is a false religious leader.
The Thessalonians were mostly Greeks who did not first think of the Jewish Temple when Paul used the word "temple." They knew Paul in person and understood him better than we do. The Thessalonians knew of Paul's spiritual Holy Temple and did not think their faith was in peril when the Jewish Temple was torn down.
Another reason to think that Paul did not think that the Temple in Jerusalem was the Temple of God comes from these verses in Luke.
44 It was now about noon, and darkness came over the whole land until three in the afternoon,
45 for the sun stopped shining. And the curtain of
the temple was torn in two
Luke 23:44-45 NIV
The curtain of the temple refers to the curtain around the Holy of Holies. I don't believe that God is finished with the Jewish people. It does look like the ripping of the sacred curtain of the Holy of Holies is a sign that God is finished with the Jerusalem Temple at that point. This is another reason to believe that Paul was thinking of God's spiritual temple in 2 Thessalonians 2:3-4.