vic said:
May I see some Scripture that supports this?
It may go back even to scripture. The view of one Bible scholar:
"The second of the problems mentioned above -- if Jesus expected God to change the world, he was wrong -- is by no means novel. It arose very early in Christianity. This is the most substantial issue in the earliest surviving Christian document, Paul's letter to the Thessalonians. There, we learn, Paul's converts were shaken by the fact that some members of the congregation had died; they expected the Lord to return while they were all still alive. Paul assured them that the (few) dead Christians would be raised so that they could participate in the coming kingdom along with those who were still alive when the Lord returned. The question of just how soon the great event would occur appears in other books of the New Testament. A saying in the synoptics (discussed more fully below) promises that 'some standing here' will still be alive when the Son of Man comes. In the appendix to the Gospel of John (ch. 21), however, Jesus is depicted as discussing an anonymous disciple, called 'the disciple whom Jesus loved', with Peter: 'If it is my will that he remain until I come, what is that to you?' The author then explains, 'So, the rumour spread in the community that this disciple would not die. Yet Jesus did not say to him that he would not die, but "If it is my will that he remain until I come, what is that to you?"' (John 21.21-3).
The history of these adjustments to the view that God would do something dramatic while Jesus' contemporaries were still alive is fairly easy to reconstruct. Jesus originally said that the Son of Man would come in the immediate future, while his hearers were alive... Then, when people started dying, they [the followers of Jesus] said that some would still be alive. When almost the entire first generation was dead, they maintained that one disciple would still be alive. Then he died, and it became necessary to claim that Jesus had not actually promised even this one disciple that he would live to see the great day. By the time we reach one of the latest books of the New Testament, 2 Peter, the return of the Lord has been postponed even further: some people scoff and say, 'Where is the promise of his coming?' But remember, 'with the Lord one day is as a thousand years, and a thousand years as one day' (2 Peter 3.3-8). The Lord is not really slow, but rather keeps time by a different calendar.
In the decades after Jesus' death, then, the Christians had to revise their first expectations again and again. This makes it very probable that the expectation originated with Jesus. We make sense of these pieces of evidence if we think that Jesus himself told his followers that the Son of Man would come while they still lived. The fact that this expectation was difficult for Christians in the first century helps prove that Jesus held it himself. We also note that Christianity survived this early discovery that Jesus had made a mistake very well."
E.P. Sanders (1993) The Historical Figure of Jesus, Penguin.