N. T. Wright, in The Resurrection of the Son of God, is well known for making the argument that Jesus must have been raised from the dead bodily because nothing short of a literal resurrection could explain how the disciples came to believe it, in spite of the Jewish theology of that time. He argues that in Second Temple Judaism the concept of the resurrection was that it would happen at the "last day," (Greek is eschaton) and would usher in the "new age" (i.e., the kingdom). On that last day, Abraham, Isaac, Jacob and other saints would be raised and the kingdom of God would begin. Since that obviously didn't happen when Jesus was said to be raised from the dead, no Jew would have believed that Jesus was really raised from the dead unless they were eyewitnesses of it. Thus, according to Wright, Jesus must have been raised from the dead literally and bodily or the Jewish disciples would have never believed it because it ran counter to their expectations about the timing of the resurrection.
Wright is correct that Second Temple Judaism believed that the resurrection would occur at the last day at the inauguration of the Kingdom. They also believed that it would be the Messiah who would usher in that kingdom. The disciples of Jesus were of the same mind. Note that in the Gospels they are continually asking him when he is going to bring in the kingdom and what positions they will have in that kingdom. When he was executed by the Romans, their whole belief system was exploded. They had to re-think everything. They came up with a new twist on the Jewish beliefs. Using certain OT passages, they came to believe that the Messiah had to die first before the Kingdom could come. He died as a martyr. Second temple Judaism believed that the martyrs would be vindicated by being resurrected (see Daniel 12 and 2 Macabbees).
The Christian theology that evolved said that Jesus was the first-fruits of that resurrection (1 Cor. 15:20-23). The eschaton, therefore, had begun. The Christians believed that within their lifetimes, Jesus would return, they would be changed or raised (1 Cor.15:51-52) and the kingdom would be realized. Thus, when you read the NT, you find that the writers believed that the last days (eschaton) had begun. This is how they reconciled the Jewish belief in the timing of the resurrection with their belief that Jesus had been raised.
In Matthew 24:34 (I tell you the truth, this generation will certainly not pass away until all these things have happened), Jesus tells his followers that the kingdom will come in their generation.
In Acts 1:5 (So when they met together, they asked him, "Lord, are you at this time going to restore the kingdom to Israel?" ), the disciples ask Jesus before he ascends to heaven when he is going to establish the Kingdom.
In Acts 2, on the day of Pentecost, Peter explains that the "speaking in tongues" that have just occurred are proof that the last days (eschaton) have begun. He says: "Fellow Jews and all of you who live in Jerusalem, let me explain this to you; listen carefully to what I say. These men are not drunk, as you suppose. It's only nine in the morning! No, this is what was spoken by the prophet Joel:" 'In the last days, God says, I will pour out my Spirit on all people. Your sons and daughters will prophesy, your young men will see visions, your old men will dream dreams...'(2:14-17).
In Galatians 4:4 (But when the time had fully come (lit. "the fullness of time") God sent his Son, born of a woman, born under law. ), Paul states that birth of Jesus came at the end of the age.
In 1 Thess. 4:15-17, Paul indicates his belief that he will still be alive when Jesus returns. He says: 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. 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. 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.
The author of Hebrews states that the the last days began with the incarnation. He says: In the past God spoke to our forefathers through the prophets at many times and in various ways, but in these last days (eschaton) he has spoken to us by his Son... (Hebrews 1:1-2).
Interestingly enough, since Jesus didn't return in the lifetimes of the first generation of believers, some began to doubt the truth of what they had believed. The author of 2 Peter attempts to squash the doubt.
2 Pet. 3:3-4, 8-10: First of all, you must understand that in the last days scoffers will come, scoffing and following their own evil desires. They will say, "Where is this 'coming' he promised? Ever since our fathers died, everything goes on as it has since the beginning of creation." . . . But do not forget this one thing, dear friends: With the Lord a day is like a thousand years, and a thousand years are like a day. The Lord is not slow in keeping his promise, as some understand slowness. He is patient with you, not wanting anyone to perish, but everyone to come to repentance. But the day of the Lord will come like a thief. The heavens will disappear with a roar; the elements will be destroyed by fire, and the earth and everything in it will be laid bare.
Since Jesus still has not returned, Christians have had to re-think their eschatology (doctrine of last things) and have come up with several alternative explanations on when Jesus will return and when the kingdom will be established. They have also debated the nature of that kingdom. Conservative Christians today have a variety of beliefs on these matters, all insisting, of course, that their particular view is the correct one. Just to list some of the views held by conservative Christians today:
Premillennialism is the view that Jesus will return and reign on the earth for 1000 years before eternity begins. Within this view, there are at least 3 variations: 1) Pretribulational rapture says that Jesus will snatch up all believers before a 7 year tribulation period begins on the earth. After the 7 year tribulation, Jesus and his followers will return together to establish the 1000 year kingdom. 2) Midtribulational rapture says the same things as the pretribulational view except that the rapture will happen at the mid-point (3.5 years) of the tribulation. 3) Posttribulational rapture says the same things as the above views except that the rapture will happen at the end of the 7 year tribulation.
Postmillennialism is the view that the church will bring in the kingdom (not necessarily a literal 1000 year kingdom) itself and then Jesus will return. Again there are many variations within this view.
Amillennialism is the view that there will be no literal, physical kingdom on earth but that it is a spiritual kingdom and has already begun. This view, sometimes called Preterism, is becoming more popular among conservatives.
So, Christian theology, and especially eschatology, is continuing to evolve. Just as the original disciples had to re-think their theology in light of Jesus death, Christians through history and even today have had to re-think their eschatology in light of the fact that Jesus still has not returned.