1Thessalonians 4:16-18 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: Then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord. Wherefore comfort one another with these words.
‘Then we which are alive and remain.’ See the time of the rapture (2Thess. 2:7; Rev. 4:1). The rapture and the second coming of Christ:  Christ and the many saints that were resurrected after His resurrection (1Cor. 15:20, 23; Matt. 27:52-53; Eph. 4:8-10).  “Afterward they that are Christ’s at His coming” (1Cor. 15:23, 51-54; John 14:1-3; Luke 21:34-36; 2Cor. 5:1-8; Eph. 5:27; Php. 3:11, 20-21; 1Thess. 2:19; 3:13; 4:13-17; 5:9, 23; 2Thess. 2:1, 7; Col. 3:4; Jas. 5:7-8; 1Jn. 2:28; 3:2; 1Pet. 5:4). Everyone in Christ, dead or alive, will be translated at this time. Not one person will be left on earth who is in Christ (4:16-17).  The 144,000 Jews will be saved in the first 3½ years of Daniel’s 70th week (Rev. 7:1-8). They will be caught up as the manchild in the middle of this week or 3½ years before the second coming (Rev. 12:5; 14:1-5; Isa. 66:7-8; Dan. 12:1).  The great multitude of tribulation saints who are saved after the rapture 2, above and during the whole of Daniel’s 70th week (Rev. 6:1 – 19:21). The first martyrs of this period are told to rest until the rest of them are killed (Rev. 6:9-11) when vengeance will be taken and all raptured in time for the marriage supper (Rev. 7:9-17; 15:2-4; 20:4-6). Even those killed by the beast in the last 3½ years of this week have a part in the first resurrection (Rev. 20:4-6). This proves their rapture in time for the marriage supper (Rev. 19:1-10) and in time to come back with Christ (Rev. 19:11-21; Jude 1:14; Zech. 14:5).  The rapture of the two witnesses, ending the first resurrection which began with the resurrection of Christ (Rev. 11:7-11).
‘Caught up’ [Greek: harpazo] to carry off; grasp hastily; snatch up; to seize and overpower; to plunder (John 10:28). From this we get our word rapture, meaning the act of transporting, as harpazo is used in Matthew 13:19; Acts 8:39; 2Corinthians 12:2, 4; 1Thessalonians 4:17 and Revelation 12:5.
‘In the clouds’ – This no doubt refers to literal clouds instead of multitudes of people.