1 These 4:15-18 just doesn't say that the church will get raptured before the great tribulation. All it says is that Jesus will return a second time which is in agreement with the rest of New Testament prophecy.
Matthew 24 says that Jesus returns after the tribulation which would place the "rapture" as a simaltaneous event that coincides with the 2nd coming and the ending of the battle of Armageddon.
2 Thess 2: 1-12 says that a rebellion, or falling away, also known as the great apostasy of the church, before the anti-Christ sets up shop in third temple.
So here is a more accurate timeline as far as I can tell and in my humble interpretation:
0. Beginning of birth pains (where we are now)
1. Rebellion of the church
2. The rise of the anti-Christ
3. The great tribulation
4. - 8. (Most likely occuring at the same time) Return of Christ, End of the Battle of Armageddon, rapture, kingdom age, white throne judgement.