When Christ comes down from the sky, the Christ-followers who have died will rise from the grave and meet Him in the air

1 Thessalonians 4:15-18

For this we tell you by the word of the Lord, that we who are alive, who are left until the coming of the Lord, will in no way precede those who have fallen asleep. For the Lord himself will descend from heaven with a shout, with the voice of the archangel and with God’s trumpet. 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. So we will be with the Lord forever. Therefore comfort one another with these words.