4:14 if. The sense here is not one of uncertainty, but of declaration. That is, “[since] we believe that Jesus died and rose again.” Note also that there is no other condition than just this condition for a believer to participate in the resurrection and rapture. All born-again Christians, having real faith in the substitutionary death and bodily resurrection of Christ, will be caught up to be with Christ when He comes, just as will all believers who died in faith.
4:14 in Jesus. “In Jesus” here actually is “through Jesus” (Greek preposition is dia). Believers are often said to be “in Christ,” but never “in Jesus.” Our “sleep” is made only that through the real death of the human Jesus, but our souls go to be “with Christ” (Philippians 1:23), the resurrected Lord in heaven. Because He died, we only sleep, awaiting His return. Thus the believer’s death is only physical, partially illustrated by the dream state, when the body lies still in bed while the soul and spirit are very conscious and active. These “will God bring with Him” when Christ returns (see also I Thessalonians 4:13).
4:15 we. It is very significant to note that, in these relatively early years of his ministry, Paul considered it very likely that he himself would be living when Christ returned: “We which are alive and remain unto the coming of the Lord,” he said. This divinely inspired conviction proves that the rapture has always been imminent, not contingent on other events that must come first. That is why Jesus urged His disciples always to be watchful and ready for His return (e.g., Matthew 24:42,44).
4:15 prevent. “Prevent” is an earlier English way of saying “anticipate” or “precede” (from the Latin for “come before”).
4:16 shout. The “shout” is a military command; the great event is described as a military assault with the great host of heaven, under the command of an (not “the”) archangel (probably Michael—compare Jude 9; Revelation 12:7-9), penetrating Satan’s domain (i.e., “the prince of the power of the air”—Ephesians 2:2; 6:12). The Lord Jesus Himself will lead the mighty army of heaven, and Satan’s hosts are powerless to stem the tide. The old “strong man” of this world—that is, the Devil—will soon be bound, and the Lord “will spoil his house” (Matthew 12:29), raising the dead and rapturing into the air all His redeemed ones, whether living or sleeping.
4:17 caught up. “Caught up” means “raptured” (Greek harpazo; the same word is used in II Corinthians 12:2,4; Acts 8:39 and Revelation 12:5). The English word “rapture” comes from the Latin raptus, meaning “seized” or “carried away.” This verse, of course, is the classic defining passage on the great doctrine of the “rapture of the saints,” caught out of this world to be forever with the Lord.
4:17 together with them. The dead in Christ will first be resurrected, their bodies once again serving as the temples of their souls and spirits, but made immortal (see I Corinthians 15:51-54). Then those saints living at the time (quite possibly many in this present generation) will likewise receive immortal, glorified bodies like that of the Lord Jesus Himself (I John 3:2; Philippians 3:20,21), and be caught up “together with them.” Then both living and dead believers, all reunited in the rapture, will together meet the Lord in the air.