As a preface, it should be noted that at Christ’s return, not only are the alive-in-Christ raptured but the dead-in-Christ who are resurrected are raptured as well together with the alive: “Then we who are alive, who are left, will be suddenly caught up together with them in the clouds to meet the Lord in the air. And so we will always be with the Lord.” (1 Thess 4:17)
1. The first purpose for the rapture will be to rescue the church from the Antichrist’s persecution.
“And if those days had not been cut short, no one would be saved. But for the sake of the elect those days will be cut short.” (Matt 24:22, cf. v.31)
“and to you who are being afflicted to give rest together with us when the Lord Jesus is revealed from heaven with his mighty angels.” (2 Thess 1:7)
2. The second purpose for the rapture will be to unite the glorified church with Christ. (The disembodied believers who come with Christ have already been with Christ, but now they will be with him in newly resurrected bodies.)
“Then we who are alive, who are left, will be suddenly caught up together with them in the clouds to meet the Lord in the air. And so we will always be with the Lord.” (1 Thess 4:17)
“And if I go and make ready a place for you, I will come again and take you to be with me, so that where I am you may be too.” (John 14:3)
“These dressed in long white robes—who are they and where have they come from?” So I said to him, “My lord, you know the answer.” Then he said to me, “These are the ones who have come out of the great tribulation. They have washed their robes and made them white in the blood of the Lamb! For this reason they are before the throne of God, and they serve him day and night in his temple, and the one seated on the throne will shelter them.” (Rev 7:13–15)
3. The third purpose for the rapture is to remove the church from the earth before the day of the Lord’s wrath.
“and to wait for his Son from heaven, whom he raised from the dead, Jesus our deliverer from the coming wrath.” (1 Thess 1:10)
“Now when they are saying, ‘There is peace and security,’ then sudden destruction comes on them, like labor pains on a pregnant woman, and they will surely not escape. But you, brothers and sisters, are not in the darkness for the day to overtake you like a thief would…For God did not destine us for wrath but for gaining salvation through our Lord Jesus Christ.” (1 Thess 5:3–4, 9)
“Go, my people! Enter your inner rooms! Close your doors behind you! Hide for a little while, until his angry judgment is over!” (Isa 26:20)
“For just like the days of Noah were, so the coming of the Son of Man will be. For in those days before the flood, people were eating and drinking, marrying and giving in marriage, until the day Noah entered the ark. And they knew nothing until the flood came and took them all away. It will be the same at the coming of the Son of Man. Then there will be two men in the field; one will be taken and one left. There will be two women grinding grain with a mill; one will be taken and one left.” (Matt 24:37–41)