What is the Rapture?

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The basic premise of the rapture is that at some point in the last days, Jesus will return and take all the Christians to heaven. This includes bringing the Christians who have already died back and reuniting them with their earthly bodies. Of course over time there have been many false predictions as to the date of the rapture. The Bible does seem to indicate that no one will know the day or the hour.
The primary verses for belief in the rapture are listed at the bottom. There has been an ongoing discussion amongst Christians as to whether this rapture takes place before, during or after the tribulation. The tribulation is the last days when much destruction, death and disease will occur all over the earth during the reign of Antichrist. According to the dispensationalist view this end time period will last seven years.
There are good theological arguments for all three perspectives. Some people even believe there is no rapture at all which is almost the same as a post rapture view which is that after the tribulation Jesus will return and gather the Christians.
The view held by most Christians, if they do believe in the rapture, is the pre-tribulation rapture. This theory is popularized in the
Left Behind series of books and movies and staunchly defended at
RaptureReady.com. The reason for this is because there are several versus that say Christians will be spared the wrath of God and many believe that the tribulation period is the wrath of God. There are also scriptures that indicate that the tribulation is separated between the first three and a half years and the last three and a half years known as the great tribulation. Many mid-tribulation people see the later period as the wrath of God. The verses that many use to cite the rapture can easily be seen as the return of Christ at the end and so that is a credible view also.
Robert Van Kempen was a man who became independently wealthy through some business deals. He decided to take some time and come to a conclusion about the rapture. After much time and studying he concluded that a pre-wrath rapture was the answer. This theory means that a rapture will happen at some time during the tribulation but before God’s wrath takes place but the exact timeline is not known. This is unlike the mid-trib rapture which places the rapture directly in the middle of the seven year tribulation.
I personally subscribe to pre-wrath view. In Revelation chapter 7, the vision that John describes, I see as the tribulation and in the middle of that period a great multitude appear in heaven.
Supporting Scripture
13 Brothers, we do not want you to be ignorant about those who fall asleep, or to grieve like the rest of men, who have no hope. 14 We believe that Jesus died and rose again and so we believe that God will bring with Jesus those who have fallen asleep in him. 15 According to the Lord's own word, we tell you that we who are still alive, who are left till the coming of the Lord, will certainly not precede those who have fallen asleep. 16 For the Lord himself will come down from heaven, with a loud command, with the voice of the archangel and with the trumpet call of God, and the dead in Christ will rise first. 17 After that, we who are still alive and are left will be caught up together with them in the clouds to meet the Lord in the air. And so we will be with the Lord forever. 18 Therefore encourage each other with these words.
30 "At that time the sign of the Son of Man will appear in the sky, and all the nations of the earth will mourn. They will see the Son of Man coming on the clouds of the sky, with power and great glory. 31 And he will send his angels with a loud trumpet call, and they will gather his elect from the four winds, from one end of the heavens to the other.
30 "It will be just like this on the day the Son of Man is revealed. 31 On that day no one who is on the roof of his house, with his goods inside, should go down to get them. Likewise, no one in the field should go back for anything. 32 Remember Lot's wife! 33 Whoever tries to keep his life will lose it, and whoever loses his life will preserve it. 34I tell you, on that night two people will be in one bed; one will be taken and the other left. 35 Two women will be grinding grain together; one will be taken and the other left.
9 After this I looked and there before me was a great multitude that no one could count, from every nation, tribe, people and language, standing before the throne and in front of the Lamb. They were wearing white robes and were holding palm branches in their hands. 10 And they cried out in a loud voice:
"Salvation belongs to our God, who sits on the throne, and to the Lamb." 11 All the angels were standing around the throne and around the elders and the four living creatures. They fell down on their faces before the throne and worshiped God, 12 saying: "Amen! Praise and glory and wisdom and thanks and honor and power and strength be to our God for ever and ever. Amen!"
13 Then one of the elders asked me, "These in white robes—who are they, and where did they come from?"
14I answered, "Sir, you know."
And he said, "These are they who have come out of the great tribulation; they have washed their robes and made them white in the blood of the Lamb. 15 Therefore, "they are before the throne of God and serve him day and night in his temple; and he who sits on the throne will spread his tent over them.
16 Never again will they hunger; never again will they thirst. The sun will not beat upon them, nor any scorching heat. 17 For the Lamb at the center of the throne will be their shepherd; he will lead them to springs of living water. And God will wipe away every tear from their eyes."