One of the arguments among eschatologists and believers concerning the end times is the timing of the Rapture--i.e., when the believers will be caught up to heaven to meet the returning Christ. The dispute is primarily between one side that takes the position of a pre-tribulation ("pre-trib") rapture and those asserting a post-tribulation ("post-trib") rapture (although there are some mid-tribulation rapturists out there as well).
Full disclosure: I am a member of The Church of Jesus Christ of Latter-Day Saints (LDS or Mormon) which teaches a post-tribulation rapture (although we don't use those terms): that is, that the rapture will occur at or around the time Christ descends to the Earth to place his feet on the Mount of Olives.
I've never quite understood from where came the pre-trib point of view because the scriptures cited for it seemed to either have nothing to do with the timing--only that it would occur--or didn't seem to be saying what the pre-trib proponent claimed.
In the video above, Nelson Walters confirms that I was correct. Apparently one of the key verses in the New Testament relied upon by pre-tribulationists is 2 Thessalonians 2:3 which states, in the King James Version: "Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;" And, in the New International Version: "Don’t let anyone deceive you in any way, for that day will not come until the rebellion occurs and the man of lawlessness is revealed, the man doomed to destruction."
Apparently, as Walters explains in the video, the Greek word "apostasia" for "falling away" or "rebellion" uses a root meaning "departure," and so has been interpreted as a code for "rapture." That is, rather than the departure being the departure from the faith, it is interpreted by some as a physical departure from Earth.
Now, as the video explains, the same word has never been used to mean anything but rebellion or falling away in any other context; but in 1954, a scholar by the name of E. Schuyler English released a book called Re-Thinking the Rapture in which he advanced the novel reinterpretation of this verse as pertaining to the rapture rather than to an apostasy. His theory may have languished, but it was embraced by the then president of the influential Dallas Theological Seminary, John F. Walvoord, and, thereafter, quickly adopted by the Southern Baptist Convention. Although Walters doesn't come out and say it, English and Walvoord were obviously examples of those "false prophets" of which Christ warned.
The belief in the timing of the rapture has some significance to Christian preppers because it impacts whether they will physically prepare to survive through the tribulation by storing food, water, medicine, etc., or expect to be gone. Like the bumper sticker says, "In event of Rapture, this car will be empty." And I've read and heard people contend that they don't need any significant physical preparations for the last days because they believe they will be raptured before the need arises for such preparations.
More broadly, however, it also impacts the spiritual preparation. Remember the parable of the 10 virgins where the coming of the Lord took longer than expected, and 5 had insufficient oil (i.e., insufficiently grounded belief and faith) and were not prepared for when the Lord finally returned.
The latter is a real problem. Imagine for a moment that you have been raised believing in the concepts of imminence (Christ can return at any time with or without warning) and that there will be a rapture prior the tribulation. Then the tribulation hits, but you aren't swept up into heaven, and a man appears claiming to be a new Christ or Savior. You can see how such events would not only turn someone expecting to be swept up into heaven very bitter towards their religion because one of its basic teachings (a pre-trib rapture) is shown to be false and he or she has to go through a period of great tribulation, and how inviting would be the teachings of a man (the Anti-Christ) claiming he can bring peace to a troubled world.
But if you know that there will be certain signs and events that will precede Christ's return, and that you will have to live through the period of tribulation, you are more likely to have your foundation built upon stone and recognize the Anti-Christ for the charlatan he will be, and therefore weather the events of the tribulation until the return of our Lord and Savior.