THE 7 year period of Jacob's trouble (Jeremiah 30:7), which is Daniel's seventieth week (Daniel 9:27), is the time of the antichrist. It will last from right after the rapture up until the second advent of Christ. This chapter is devoted to describing the order and nature of this particular future period of seven years. As we saw in the last chapter, the Thessalonians feared that they were already in the middle of this era. Paul makes it abundantly clear that such was not possible.
Before the Tribulation and the day of Christ, several things must happen. First, there has to come a major event which Paul calls "a falling away" - a major apostasy within Christianity (vs. 3). It could be argued that this has occurred already, but it can and will get much worse in the future. The second necessity is that the Holy Ghost be removed from the earth (vs. 7). After Christ's resurrection and ascension up to heaven, the Holy Spirit was sent to comfort and indwell believers (as well as to rebuke sinners). When the rapture occurs, the temple of the Holy Spirit on earth (the church) will be totally removed. With the church will go that morally restraining influence, whom we know to be the Holy Spirit. The third precondition is actually a signal that the Tribulation has begun: it will be the revelation of the identity of the antichrist (vs. 3-4 & 8-10). The church will not know the identity of this awful leader. We will be gone before He takes over the world.