How can it be said that Paul taught a pre-tribulational rapture of the Church given 2 Thessalonians chapter 2? 2 Thess 2:1-3: Now concerning the coming of our Lord Jesus Christ and our being gathered together to him, we ask you, brothers, not to be quickly shaken in mind or alarmed, either by a spirit or a spoken word, or a letter seeming to be from us, to the effect that the day of the Lord has come. Let no one deceive you in any way. For that day will not come, unless the rebellion comes first, and the man of lawlessness is revealed, the son of destruction.

Paul appears to be saying that &quot;that day&quot; (the day of the Lord's coming and our being gathered to him) will not come unless two conditions (the rebellion and the revelation of the lawless one) come first.  According to pre-tribulational rapture theory the rapture of the Church takes place well in advance of both of these conditions.  If he is writing to reassure his pre-trib rapture followers that the Second Coming of Christ (Day of the Lord) hasn't happened yet, why has he listed two conditions that they will not be around to witness?  Why not say, for instance, &quot;The rapture comes first and you're still here aren't you?&quot;
There are a few interpretations:


The falling away (or rebellion) is the word apostasia (G646). Some say this apostasia, or the apostasy, is the rapture. However, there are some problems with this interpretation: literally it would mean that the rapture comes before the gathering unto Him, which doesn't make sense (since in this interpretation the gathering is the rapture.) The other problem is that the word apostasia has a bad connotation, it is only used for a departure which is negative, not something positive like a rapture. Another argument is that the definition of apostasy is: the abandonment or renunciation of a religious or political belief or principle.
Some say the coming of our Lord Jesus Christ is the rapture, and our gathering together unto him is the second coming. Doing this makes it possible for them to interpret the next verses so that it's only talking about the second coming, so pretrib rapture not included. I have no idea what justifies it to say the coming is the rapture and our gathering is the second coming or vice versa, because it has no biblical basis.
Some say that the Thessalonians received a letter from someone claiming that the day of the Lord had already come. They say the coming of our Lord Jesus Christ and our being gathered together to him is only about the second coming. This would mean that Paul is just saying that the day of the Lord can't have happened since the falling away and antichrist has yet to come. The problem here is that Paul writes: or a letter seeming to be from us, if this theory would've been true, he would've written something like "a letter from someone else." To work around this issue some say that the letter that the Thessalonians received was written like it was coming from one of the apostles, ofcourse this is pure speculation. But don't get me wrong, it is possible that the Thessalonians did think that the day of the Lord had already come, since verse 2 could imply this. But if this is true, and the pretrib rapture theory is true, then how could the Thessalonians believe the day of the Lord was already at hand, since nobody was raptured?
Another argument I've heard is "the antichrist is already in this world." Which also has some problems: he, the antichrist isn't revealed yet, so that's no reason to justify the pretrib theory. Also the restrainer talked about in verse 6 to 8 is the church (or holy spirit) in the pretrib rapture theory: the church has to be raptured before the antichrist comes down to earth. This is a serious problem: if the antichrist is already here it would mean we were already been raptured.