What does 1 Thessalonians 4:15 mean?

This passage is meant to clarify misunderstandings about the nature of the end times, as well as what happens to Christians who die before the return of Jesus Christ. Writing to the believers at Thessalonica by divine revelation, Paul declares living Christians will not be caught up—"raptured"—ahead of departed Christians at the coming of the Lord. He commends the Thessalonian believers for waiting for God's Son from heaven (1 Thessalonians 1:10). Upcoming verses will contain Paul's teaching that Jesus' return involves an imminent, immediate reunion with Christ for all who believe in Him.

Paul believed this sudden, physical reunion—referred to as "the rapture"—could happen at any time. He told the Corinthians, "the appointed time has grown very short" (1 Corinthians 7:29). In Philippians 4:5, he announced that "The Lord is at hand." He wrote to Titus about leading a self-controlled, upright, and godly life while "waiting for our blessed hope, the appearing of the glory of our great God and Savior Jesus Christ" (Titus 2:13). His words to Titus show us that we must not wait passively for our Lord's return, but we should actively engage in a godly life. The apostle John affirmed the truth that the hope of being raptured compels us to purify ourselves (1 John 3:2–3).

Someday, perhaps even today, Jesus will come for all who have trusted in Him as their Savior. His return will fulfill the promise He made in John 14:3: "If I go and prepare a place for you, I will come again and will take you to myself…"

Paul's reference to those who have "fallen asleep" points to those Christians who have already died. As shown in the prior verse, these believers will be taken just as much as those who are alive when Jesus returns. Paul's other writings clarify that this "sleep" is simply a metaphor for their temporary condition—a reference to the material body—not a state of spiritual unawareness (Philippians 1:20–24; 2 Corinthians 5:8; see also Luke 16:19–31).