Pre-tribulation rapture is based on some considerable speculations. One of these relates to II
Thessalonians 2:6 where the verse indicates that some power, probably the Holy Spirit, is restraining evil from running its full course until the appointed time. Pre-tribulation theorists extend this to meaning that when this restraint is removed this somehow automatically means that the Holy Spirit
is completely removed from the earth and thus the believers with it. But then, where do the great
multitude of saved which no man can number (who are killed in the tribulation) come from?
(Revelation 7:9,14). Surely you can’t say that a great work of God occurs on the earth without the
Holy Spirit? It makes a lot more sense to see that these are the saints that enter into the tribulation period, not a whole new breed saved during it. (Though of course many people may be saved during
it as well.)
Besides, the II Thessalonians 2 passage is actually evidence that the rapture is not pre-tribulation.
Paul is speaking against those who were saying that the day of Christ was imminent at that time or
had already passed; pointing out that the day of Christ won’t come until after the Antichrist is
revealed. So he actually gives Christians the sign of the Antichrist as preceding their expectation of Christ’s return.