They are being identified as those who have fallen asleep. You must identify who you are talking about. He is talking about the dead. They died first and then are taken up. They did not go to heaven first before they died. ???
So in verse 15 you are then having to say that the dead in christ were spiritually resurrected a split second before the raptured people were changed? After all it would have to mean that if the raptured folks don't precede the asleep/dead in Christ.