Then they also which are fallen asleep in Christ are perished.
Fallen asleep in Christ - in communion with Christ as His members. 'In Christ's case the term used is death, to assure us of the reality of His suffering; in ours, sleep, to give us consolation. In His case, His resurrection having taken place, Paul shrinks not from the term death; in ours, the resurrection being still only a matter of hope, he uses falling asleep' (Photius, 'Quaestiones Amphilochiae,' 197).
Perished. Their souls are lost in misery in the unseen world.