10. Who died. From the design of Christ’s death he confirms what he has said, for if he died with this view—that he might make us partakers of his life, there is no reason why we should be in doubt as to our salvation. It is doubtful, however, what he means now by sleeping and waking, for it might seem as if he meant life and death, and this meaning would be more complete. At the same time, we might not unsuitably interpret it as meaning ordinary sleep. The sum is this—that Christ died with this view, that he might bestow upon us his life, which is perpetual and has no end. It is not to be wondered, however, that he affirms that we now live with Christ, inasmuch as we have, by entering through faith into the kingdom of Christ, passed from death into life (John 5:24). Christ himself, into whose body we are ingrafted, quickens us by his power, and the Spirit that dwelleth in us is life, because of justification.
—John Calvin on 1Thessalonians 5:10 (HT: Brian Lund)