1 Thessalonians 4:17 - Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord.
What is the "rapture"
The reality of the rapture
No doubt the miraculous ascent of Christ will be repeated corporately in the life of every Christian. If a Christian has already went to be with the Lord in death, then that saint will be resurrected in a new body and then raptured, followed immediately by the living saints' bodies being transformed and raptured upon Christ's return. 1 Thessalonians 4:13-18 gives us the fullest treatment of this mass miracle. Other passages too give hints to the details surrounding this event in passages such as Matthew 24; 1 Thessalonians 5; 2 Thessalonians 2 and 1 Corinthians 15:50-57.
The question about the rapture's timing and occurrence
When studying Bible prophecy or eschatology three headings can be used in categorizing Bible doctrine: definites, positions and opinions. Definites include those teachings which determine salvation, positions have to do with those areas or distinctives that entire denominations or church groups teach. Opinions of course refer to those areas of Biblical teaching that though important, yet because of relative lack of information result in allowances for legitimate disagreement. In regards to the timing of the rapture, we would have to state that a number of opinions exist as to when it will occur.
Pre-trib, Mid-trib or post-trib?
Questions of course center around whether or not the church will be raptured "before", "mid-way" or "towards the end" of this period. The opinions are respectively referred to as "Pre-trib", "mid-trib" and "post-tribulationalism". The diagrams below summarize these positions (from website link: en.wikipedia.com)
So why does the rapture matter?