rapture

I know many do not believe in a pre-tribulation rapture. I don't understand why, It is clear from scripture that there will be people (SAINTS) left after the second coming who will repopulate the earth. This can not happen if all are changed to immortal bodies at the second coming. As far as pre wrath the whole tribulation is Gods wrath! Therefore it must be pre-trib rapture! Can anyone explain another way this can happen?