The Bible is pretty clear that no man knows the time and place of when Jesus Christ will return to collect His church and return to Heaven with them. We do know that it will happen at some point in time. The Apostle Paul gave a very clear description of the rapture event in his letters to the Thessalonians and Corinthians.

1 Thessalonians 4:16-18 (NIV)

¹⁶ For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. ¹⁷ After that, we who are still alive and are left will be caught up together with them in the clouds to meet the Lord in the air. And so we will be with the Lord forever. ¹⁸ Therefore encourage each other with these words. (1)

1 Corinthians 15:51-53 (NIV)

⁵¹ Listen, I tell you a mystery: We will not all sleep, but we will all be changed— ⁵² in a flash, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, the dead will be raised imperishable, and we will be changed. ⁵³ For the perishable must clothe itself with the imperishable, and the mortal with immortality.(2)

Now the reason I give you for a Pretribulation Rapture is really quite simple and comes from common sense. Just think for a moment, what is stopping the antichrist from taking complete control? What is the obstacle in his path?  Christians! Is the answer! What is inside all of us? The Holy Spirit! That is what is standing in the way of the antichrist! Before the antichrist can come to power Jesus Christ will return and take his Church up to heaven. The obstacle that is in the way of the antichrist is the Holy Spirit in all Christians; it is what is binding him at this very moment.  The Rapture of the Church MUST come before the Tribulation.