Why do the dead in Christ rise before the living are changed at the rapture?

Scripture states that the living who remain shall not precede those asleep in Christ; the dead in Christ must rise first. Their souls and spirits are brought from heaven to the atmosphere, and their resurrected bodies are brought out of the tomb and reunited with them before the living are changed.

Les explains from I Thessalonians 4:15-17 that the living and remaining believers will not go ahead of those who have died. The Lord Himself descends from heaven with a shout, with the voice of the archangel, and with the trump of God, and the dead in Christ rise first. Those who must be resurrected are brought out of the tomb, wherever they are buried, and reunited with their soul and spirit, which God has brought from His presence into the atmosphere. Only then will the living, who have not died, be changed in the twinkling of an eye.

1 Thessalonians 4:16

For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first:

How are the dead in Christ raised — what happens to the body and to the soul and spirit?

At the resurrection, the dead in Christ rise first: their bodies are brought out of the grave, wherever buried, and are reunited with their soul and spirit. Meanwhile, the soul and spirit of believers, absent from the body, are present with the Lord and are brought by God from heaven into the atmosphere for that reunion.