John Calvin Commentary 1 Thessalonians 4:15

"For this we say unto you by the word of the Lord, that we that are alive, that are left unto the coming of the Lord, shall in no wise precede them that are fallen asleep." — 1 Thessalonians 4:15 (ASV)

For this we say unto you. He now briefly explains how believers will be raised from death. Now, as he speaks of something very great, incredible to the human mind, and also promises what is beyond human power and choice, he states first that he does not present anything of his own, or that comes from humans, but that the Lord is its Author.

It is probable, however, that the word of the Lord means what was taken from his discourses. For though Paul had learned by revelation all the secrets of the heavenly kingdom, it was, nevertheless, better suited to establish the belief of a resurrection in the minds of believers when he related those things that had been spoken by Christ's own mouth. “We are not the first witnesses of the resurrection; instead, the Master himself declared it.”

We who live. He said this so that they would not think that only those who would be alive at the time of Christ's coming would share in the resurrection, and that those who had previously been taken away by death would have no part in it. “The order of the resurrection,” he says, “will begin with them: we will therefore not rise without them.”

From this it appears that the belief in a final resurrection had been, in the minds of some, slight and obscure, and involved various errors, since they imagined that the dead would be deprived of it. For they imagined that eternal life belonged only to those whom Christ, at his last coming, would find still alive on the earth. To remedy these errors, Paul assigns the first place to the dead, and then teaches that those who are at that time remaining in this life will follow.

However, regarding the fact that by speaking in the first person he makes himself, as it were, one of those who will live until the last day, he means by this to arouse the Thessalonians to wait for it, and even more, to hold all believers in suspense, so that they may not expect it at some particular time. For even if he knew by a special revelation that Christ would come at a somewhat later time, it was nevertheless necessary that this doctrine should be delivered to the whole Church, so that believers might be prepared at all times.

Meanwhile, it was necessary to cut off all pretext for the curiosity of many in this way—as we will find him doing later at greater length. When, however, he says, we that are alive, he uses the present tense instead of the future, according to the Hebrew idiom.