1Thessalonians 4:15 For this we say unto you by the word of the Lord, that we which are alive and remain unto the coming of the Lord shall not prevent them which are asleep.
‘By the word of the Lord.’ This means by revelation (Gal. 1:12).
‘Coming of the Lord.’ The coming in the air (4:17), not His second coming to the earth of Zechariah 14:1-21; Revelation 19:1-21; Matthew 24:29-31; 25:31-46 and Jude 1:14.
These two comings should not be confused. The scriptures that apply to one do not apply to the other. Not one passage refers to both events as if they were one. These two distinct comings are separated by several years, so they aren’t two stages or phases of one coming.
The rapture is the first of the two comings, not a coming to earth but in the air. It could not be the second coming because Christ does not come to the earth to live here and fulfil a mission as He did at the first coming. When Christ meets the saints in the air He takes them to heaven with Him and presents them before the Father’s throne where they remain during the time the tribulation is running its course on the earth (3:13; John 14:1-3). Christ does not remain in the air with the saints when they meet Him as in 1Thessalonians 4:13-17. The marriage supper and the judgment of saints take place in heaven, then at the second coming after the tribulation, Christ and the saints leave heaven together to come down to the earth (2Cor. 5:10; Rev. 19:1-21). The rapture is the time Christ comes for the saints to take them to heaven.
The second coming is the time He comes to the earth to live here and fulfil a mission. This is the time He comes from heaven with the saints, having raptured them at least seven years before. The second coming cannot take place until all of Revelation 1:1-19:21 is fulfilled while the rapture can take place any moment without anything being fulfilled.