If you study the Scripture a little closer, you will find the ones being gathered are the ones going into judgement before the Kingdom is established. The ones left are the ones entering into the Kingdom.
Neither are the members of Christ's body - the church.
Read Matthew 24 followed by Revelation 20 and find the chronology as given in God's ordered word, without switching the order: (Great tribulation -> Son of Man in the clouds of heaven -> The body of Christ alive at the time, with the dead in Christ resurrected meets Christ in the clouds -> The remainder of the people on earth is destroyed -> Christ descends with his resurrected and alive elect from the last generation to earth -> 1000 years Millennial kingdom commence -> At the end of the 1000 years Millennial kingdom the battle of Gog and Magog takes place with Christ Yeshua and the saints conquering -> The remainder of the dead is resurrected -> The great throne judgement-> The damned go to the lake of fire -> The old heaven and earth dissolves, and the new heaven and new earth is introduced, where God's elect dwells with him and Christ Yeshua for eternity
Matthew 24 (New King James Version)
29“Immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light; the stars will fall from heaven, and the powers of the heavens will be shaken. 30Then the sign of the Son of Man will appear in heaven, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of heaven with power and great glory. 31And He will send His angels with a great sound of a trumpet, and they will gather together His [d]elect from the four winds, from one end of heaven to the other. 39... so also will the coming of the Son of Man be. 40Then two men will be in the field: one will be taken and the other left ("behind"). 41Two women will be grinding at the mill: one will be taken and the other left ("behind").
Revelation 20 (New King James Version)
4Then I saw the souls of those who had been beheaded for their witness to Jesus and for the word of God, who had not worshiped the beast or his image, and had not received his mark on their foreheads or on their hands. And they lived and reigned with Christ for [a]a thousand years. 5But the rest of the dead did not live again until the thousand years were finished. This is the first resurrection. 7Now when the thousand years have expired, Satan will be released from his prison 8and will go out to deceive the nations which are in the four corners of the earth, Gog and Magog, to gather them together to battle, whose number is as the sand of the sea. 9They went up on the breadth of the earth and surrounded the camp of the saints and the beloved city. And fire came down from God out of heaven and devoured them. 12And I saw the dead, small and great, standing before [c]God, and books were opened. And another book was opened, which is the Book of Life. And the dead were judged according to their works, by the things which were written in the books.
Revelation 21 (New King James Version)
1Now I saw a new heaven and a new earth, for the first heaven and the first earth had passed away. 3And I heard a loud voice from heaven saying, “Behold, the tabernacle of God is with men, and He will dwell with them, and they shall be His people. God Himself will be with them and be their God.