Paul says that
(1)the resurrection of the dead will precede the second
coming.
According to Paul, the Lord will command those who have
suffered human death to rise. Only then
(2) will those still living at the end of time join the
resurrected dead. Both groups together
(3) will be witnesses to Christ's coming.
1 Thessalonians 4:16-18
For the Lord himself, with a word of command, with the
voice of an archangel and with the trumpet of God, will
come down from heaven, and the dead in Christ will rise
first. Then we who are alive, who are left, will be caught
up together with them in the clouds to meet the Lord in
the air. Thus we shall always be with the Lord.
Therefore, console one another with these words.