Thank you for the interpretative question on I Thess. 4:16, “What does it mean that the dead in Christ shall rise first in 1 Thessalonians 4:16?”
In seeking to answer this question, one should consider the context of the surrounding verses which may provide insight as to the the interpretation of I Thess. 4:16.
The broader context of I Thessalonians 4:16 says this, “Brothers and sisters, we do not want you to be uninformed about those who sleep in death, so that you do not grieve like the rest of mankind, who have no hope. 14 For we believe that Jesus died and rose again, and so we believe that God will bring with Jesus those who have fallen asleep in him. 15 According to the Lord’s word, we tell you that we who are still alive, who are left until the coming of the Lord, will certainly not precede those who have fallen asleep. 16 For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. 17 After that, we who are still alive and are left will be caught up together with them in the clouds to meet the Lord in the air. And so we will be with the Lord forever” (NIV).
When one reads this passage, there is a flashback to the words found in John 14. Jesus said these words to his disciples prior to his crucifixion, “Do not let your hearts be troubled. You believe in God[a]; believe also in me. 2 My Father’s house has many rooms; if that were not so, would I have told you that I am going there to prepare a place for you? 3 And if I go and prepare a place for you, I will come back and take you to be with me that you also may be where I am. 4 You know the way to the place where I am going” (NIV).
The Thessalonian believers heard that Jesus will return for the believers. There was the thought that those who have died between the ascension of Christ and the return of Christ will be left in the grave. Jesus was coming to take those who are alive to be with him. The dead in Christ will remain dead until the resurrection at the final judgment.
The Apostle Paul corrected the thought thinking of the believers had of the dead in Christ and the ones who are alive at his coming. Paul says that upon Christ return, those believers who have died after his ascension will be resurrected to life and then those who are alive will join them to be with the Lord in the air. In other words, the deceased believers will not remain in the grave. They will come out of the grave first with a new body and then the believers who are alive will be taken up to be with Jesus with a new body. Thus the dead in Christ and the alive in Christ will become one family.
There will not be a time separation or lag between the dead in Christ and the alive in Christ. There will be no separation between the dead in Christ and those alive in Christ. They will all be alive in Christ at his return. No one will be left behind, not even the deceased believers.
It would be sad to think that those who are alive are with Christ in heaven but their deceased ones are still left in the grave. This is not the case. Every believe in Christ will be united together in heaven with the dead in Christ having a slight head start as they will ascend first and then the remaining believers on earth to join them.
This resurrection or rapture of believers is debated as to when this will happen. There are those Christians who believe that Jesus will come before the Great Tribulation and then there are those Christians who believe that Jesus will come at the end of the Great Tribulation. In either case, believers in Christ will be raptured to be with him.
SUMMARY: The deceased believers are not left behind in the tomb when Jesus comes for the believers.