Who are the dead in Christ? Who is Paul talking about in 1 Thessalonians 4:16?

TL;DR:

The dead in Christ are believers who have already died. The dead in Christ will receive a new body upon Christ's return, at which time all believers will be united together with the Lord for eternity.

what does the bible say?

The term "dead in Christ" refers to believers who have died but are spiritually united with Christ. The Old Testament hints at resurrection and life beyond death, as seen in Job’s faith in a Redeemer, David’s confidence in deliverance from Sheol, and Daniel’s prophecy of future resurrection. In the New Testament, this concept is clarified: those who have died in faith will be resurrected first at Christ’s return, receiving new, immortal bodies (1 Thessalonians 4:13–17; 1 Corinthians 15:50–58). They dwell in God’s presence and will be reunited with living believers for eternity (Revelation 14:13). This promise provides hope and encouragement, affirming that death for believers is not an end but a transition to eternal life with Christ.

from the old testament

The Old Testament does not explicitly address the "dead in Christ" since Christ's resurrection and the detailed hope for believers' resurrection were fulfilled in the New Testament. However, the Old Testament does contain several passages that hint at or imply a belief in resurrection and the afterlife:
Job is likely the oldest book in the Bible. In Job 19:25–26, Job expresses a profound faith in a Redeemer who will ultimately vindicate him. This passage reflects a belief in resurrection and seeing God after death, indicating an early understanding of life beyond the grave.
Psalm 16:10 reads, "For you will not abandon my soul to Sheol, or let your holy one see corruption." David expresses confidence that God will not leave him in Sheol (the realm of the dead) and that he will not undergo decay. This verse is often interpreted as a prophecy concerning the resurrection of Christ (Acts 2:27), but it also reflects an Old Testament belief in God’s ultimate deliverance from death.
Daniel 12:2 describes a future resurrection where some will receive eternal life and others will face judgment. This passage is one of the clearest Old Testament references to resurrection and judgment, aligning with later New Testament teachings on the resurrection of the dead.

from the new testament

First Thessalonians 4:13–14 explains that those who are asleep refer to Christians who had already died. They would not experience the return of Christ while still alive. As a result, some believers were unclear regarding what would happen to these believers when Christ came again.
Christians who have already died will have their bodies come out of the grave first, immediately followed by those still alive (1 Thessalonians 4:15–17). The living and the resurrected will be “caught up together … in the clouds to meet the Lord in the air” (1 Thessalonians 4:17).
The last part of 1 Thessalonians 4:17 notes, "so we will always be with the Lord." All believers will be with Christ forever in new bodies from that point forward. 1 Thessalonians 4:18 concludes this section by stating, "Therefore encourage one another with these words."
First Corinthians 15:50–58 speaks about the new immortal body believers will receive.
Revelation 14:13 shows us the blessing of those who die in faith. It highlights that they find rest and their righteous deeds are remembered, affirming that their lives have been honored and rewarded by God.

implications for today

Prophecy is meant to produce encouragement for the believer, not fear. Paul's readers were to gain inspiration from this teaching, knowing that believers in Christ who had died were already with the Lord and would even have a new body given to them upon Christ's return, at which time all believers will be united together with the Lord for eternity. In summary, the dead in Christ are believers who have already died. However, these believers now dwell in God's presence, will one day receive a new, glorious body, and will be reunited with all believers living today at the moment of His return. Though the death of a believer produces sadness for those who remain, we can take joy in the fact that they live on with the Lord and that we who believe will one day see them again.

understand

The "dead in Christ" are Christians who have died but remain spiritually united with Christ.
The dead in Christ will be resurrected first at Christ's return, receiving new, immortal bodies.
The dead in Christ will be forever with Christ, along with all other believers, in His presence.

reflect

How does the promise of the resurrection for the "dead in Christ" affect your view of death and the afterlife?
In what ways can the hope of being reunited with deceased loved ones in Christ comfort and encourage you in times of grief?
How does knowing that believers who have died are already with the Lord influence your daily walk with God and your perspective on His promises?

engage

What happens after death is a huge question and concern for many people. The Bible teaches that at death, people will either go to a temporary hell (until Christ comes and casts Satan and all who reject God in the lake of fire) or to heaven with God. What does this reveal about the finality of the decision we make to surrender to or reject Christ?
How do Old Testament hints about resurrection, such as those in Job, Psalm 16, and Daniel, shape our understanding of the New Testament teachings on the "dead in Christ"?
How does the assurance of what happens to the dead in Christ reinforce the hope and assurance we have in the resurrection and eternal life with Christ? Why should we be compelled to share this hope and assurance with others?