First, there is this excerpt from a piece by the Rev. Charles Sutton of Trinity Episcopal Church in Whitinsville, MA:
Over the whole course of the Christian faith, there have been those who do not believe that Jesus rose from the dead. Usually those who have denied his resurrection have been those who did not believe in him as the Messiah. However, for the last century or so, there have been many people who try to say that they worship God through Jesus but who do not believe that Jesus was physically raised from the dead. They claim that belief in a physical resurrection is from a credulous age and that we know better now. They explain the resurrection as wishful thinking , as mass hallucination, or as a recognition that Jesus lives on in his teaching and in the powerful memories he leaves behind. Resurrection is, at best, a "spiritual" event, not a physical one. ...
When the Apostles proclaimed Jesus as Messiah, they risked their very lives. Unbelieving Jews hated the idea of Jesus as the Messiah. The Romans wanted no rivals to Caesar as Lord. The Apostles said that they knew that Jesus was Messiah because he rose from the dead. If they had invented the story as a way to get attention, it would not have been long before one of them, threatened with death, would have said, "You know, Jesus was a wonderful man, but he is still in the tomb. We wanted him to be the Messiah, but he has died." If the resurrection was not a physical event, the Apostles would surely have decided that a pretty story was not worth dying for.
But in fact, every Apostle except John was executed, and even John endured years of prison. They were utterly convinced that they had met Jesus in the flesh after Good Friday. He was not a cherished memory, so powerful that it was as though he were still alive. They had not seen a spirit. Everyone in those days believed in ghosts. Seeing the spirit of one who had died was not that special. A ghost might be frightening, but seeing it would not persuade anyone that the deceased was worth dying for. It would not have motivated them to proclaim a risen Lord. ...
The full, physical resurrection of Jesus affirms that creation was indeed "very good." The physical is not merely a stage needed for full development; it is good in itself. The full physical resurrection also affirms the fullness of redemption. It is not only our souls that are saved; it is the totality of each individual who belongs to Jesus. ...
When Jesus rose from the dead, he was the first installment of what would come at the last great Day. We who took to him will be raised, in bodies fit for all eternity and with spirits that trust him completely and joyfully. And the whole physical creation will also be raised and restored. The book of Revelation speaks of a "new heaven and a new earth," one that is no longer sullied by sin and deformed by death. The resurrection of Jesus is a foretaste and a guarantee that all this earth, so wonderful even in its fallen state, will not be wasted or left behind.
And then there's this excerpt from the Rev. Richard R. Losch of St. James' Episcopal Church in Livingston, AL:
Without a faith in the Resurrection of Christ, it is unlikely that the Church would ever have survived. Jesus' moral and ethical teachings contained little that was new. They are consistent with most of those of the Jewish prophets, as well as with those of other morally-focused religions of the time. His teachings and his Messiahship would have relegated him to the rank of charlatan or madman had they not been authenticated by his Resurrection. Even his crucifixion was consistent with the fate of most of the prophets, and was even similar to the fate of the founders of many other world religions. It was his Resurrection that made all the difference.
Without the Resurrection, "the Way" (as Christianity was originally called) would probably have survived at most a few years and then would have disappeared or would have been absorbed into some other movement, just as the movement begun by John the Baptist was absorbed into Christianity. Without the Resurrection, it is unlikely that the name of Jesus of Nazareth would be known at all today, even as a mention in some ancient document.
The Resurrection, then, is the basis of our faith. Among other things, it authenticates Jesus' divinity, and proves to us (through faith) that he was not just a great teacher of two millenia ago, but was truly the incarnate Son of God, the Second Person of the Holy Trinity.