15 For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent prevent: or, come before, or, anticipate, or, precede them which are asleep.
English Standard Version
15 For this we declare to you by a word from the Lord,Or by the word of the Lord that we who are alive, who are left until the coming of the Lord, will not precede those who have fallen asleep.
15 And then this: We can tell you with complete confidence - we have the Master's word on it - that when the Master comes again to get us, those of us who are still alive will not get a jump on the dead and leave them behind. In actual fact, they'll be ahead of us.
New King James Version
15 For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord will by no means precede those who are asleep.
New Living Translation
15 We tell you this directly from the Lord: We who are still living when the Lord returns will not meet him ahead of those who have died.
Matthew Henry's Commentary on 1 Thessalonians 4:15
Here is comfort for the relations and friends of those who die in the Lord. Grief for the death of friends is lawful; we may weep for our own loss, though it may be their gain. Christianity does not forbid, and grace does not do away, our natural affections. Yet we must not be excessive in our sorrows; this is too much like those who have no hope of a better life. Death is an unknown thing, and we know little about the state after death; yet the doctrines of the resurrection and the second coming of Christ, are a remedy against the fear of death, and undue sorrow for the death of our Christian friends; and of these doctrines we have full assurance. It will be some happiness that all the saints shall meet, and remain together for ever; but the principal happiness of heaven is to be with the Lord, to see him, live with him, and enjoy him for ever. We should support one another in times sorrow; not deaden one another's spirits, or weaken one another's hands. And this may be done by the many lessons to be learned from the resurrection of the dead, and the second coming of Christ. What! comfort a man by telling him he is going to appear before the judgment-seat of God! Who can feel comfort from those words? That man alone with whose spirit the Spirit of God bears witness that his sins are blotted out, and the thoughts of whose heart are purified by the Holy Spirit, so that he can love God, and worthily magnify his name. We are not in a safe state unless it is thus with us, or we are desiring to be so.