It's just too strange that you can read 1 Thess 4 and come away not understanding it when it says ..."that we who are alive, who are left until the coming of the Lord, will not precede those who have fallen asleep"....."Will Not Precede". That's because the dead in Christ will rise first and go and be with the Lord. The one's that are left...are the alive christians that are raptured. They have to change in a twinkling of an eye because they can not be in the flesh when they go to be with Jesus. Now whether that is in the glorified body or a spirit body...I do not know. (I prefer to believe it is a spirit body). But the resurrection does not occur until the 1000 year reign of Christ. That is sometime after the rapture of the church.