Scientific hypotheses regularly include the supposition of new, often unobserved entities such as quarks, strings, gravitons, black holes and the like. Is the hypothesis that God raised Jesus from the dead any less believable? Does it fit with the observable data? Is it true?
Without the resurrection, Christianity isn't only completely worthless, it is untrue. We might as well shut up and go home. The Bible itself says :
"If Christ has not been raised, our preaching is useless and so is your faith. More than that, we are then found to be false witnesses about God, for we have testified about God that he raised Christ from the dead."
Paul, the guy who wrote this, was a Jewish pharisee, who hated and persecuted the early Christians. He was the last person on earth you'd have expected to become a Christian, but he did, dramatically, after seeing a blinding vision (a bit like when you suddenly realise that you haven't done your tutorial sheet, and you only have two minutes to think of a good excuse before the lift arrives - but more life-changing). What was it that convinced him that the resurrection was an actual historical event? And how can we hope to believe in it, nearly 2000 years later?
I am going to take around ten minutes to give a brief outline of some of the evidence for the resurrection. You can find fuller treatments in some of the books on the bookstall. If God has revealed Himself in history, then that's definitely something worth checking out for yourself, rather than allowing memories of primary school nativity plays to shape your thinking about Christianity.
The Disciples' Evidence
You may be a little sceptical about taking the Biblical accounts of Jesus life as source material, as they were written by Christians. But wait! Have you ever stopped to think about why the people present at the post-resurrection appearances became Christians as a reslult? How would you feel if you met someone alive and well when you'd seen him crucified a couple of days ago? To discount the Biblical accounts because the writers were Christians is like the judge in a murder trial ruling out the evidence of everyone who'd seen the murder! They were just writing down what they'd seen so that it wouldn't get exaggerated later.
The early Christians definitely believed that the resurrection was a true historical fact, a statement corroberated by Jewish and Roman historians. You might suggest that they made up the whole story, but what did they have to gain from doing so? Most of them suffered terribly for their beliefs : they were tortured and put to death for their claims that Jesus had risen from the dead. At any time, they could have said "Oh, well, actually it didn't happen : we thought that it would be a bit of a laugh to say that Jesus came back to life. Can we go home now?"
The Burial
Today, people go on pilgrimages to Muhammed's grave. They go on pilgrimages to Confucius' grave. They even go on pilgrimages to Jim Morrison's grave. But no-one ever goes to Jesus Christ's grave to pay their last respects. Why?
Because the day after the crucifixion was the Jewish Sabbath, Jesus' body could not have been left on the cross. The account given in the gospels of Joseph of Arimathea burying Jesus is very probable, as a Christian fictional creation of a Jewish Sanhedrist (high up religious leader) doing what is right for Jesus is almost inexplicable, given their hostility towards the Sanhedrin for voting for Jesus' condemnation. So, after Jesus died, his body was put in a tomb.
The Empty Tomb
The empty tomb is one piece of objective historical evidence. Paul speaks of the it in his letters, and doesn't need to explain further, because the fact is well-known to his original audience. You may say that the story of the empty tomb was a legend which gained in credibility a generation or so after Jesus' death. However, the account contained in Mark's gospel is too early for that. The Jewish high priest at the time of the crucifixion was named Caiaphas, but Mark only ever refers to him as 'the high priest', implying that he was still in office at the time of writing. This places Mark's sources to within four years of the crucifixion (which took place in 33AD), which is clearly too short a time for an empty tomb legend to have developed. The early date of Mark is backed up by the manuscripts unearthed by archaeologists. They were circulating at a time when people who had been present at the time would have been able to put a stop to any rumours.
Another thing to note is that in the gospel accounts, the empty tomb was first observed by women, who were not qualified to serve as witnesses in the Jewish legal system. Why would the early Christian church humiliate its leaders by making up a story about them hiding in Jerusalem while the women went to the tomb? The women were known in the early Christian fellowship, and the fact that they are named means that they could not easily be associated with a false account.
So the empty tomb has to stand as a historical fact.
Possible Explanations
The earliest attempt to explain the empty tomb is recorded in Matthew's gospel, which tells us that the Jewish leaders bribed the guards (who had been placed at the tomb) to say that the disciples had come and stolen the body during the night. This explanation is ridiculous : imagine the terrified disciples, who had scattered after Jesus arrest, getting through a guard, removing the stone, stealing the body, then boldly telling the world that Jesus had risen. This explanation doesn't account for their amazing transformation from dispirited cowards into steadfast preachers who were willing to die horrible deaths for their claims. As I said earlier, the disciples definitely believed in the resurrection : it was not possible for them to have made up such a story.
Others have suggested that the disciples may have gone to the wrong grave, and jumped to the conclusion that Jesus had risen. This seems more plausible, until you remember that within seven weeks of the crucifixion thousands of people were becoming Christians and actively defying the Jewish authorities by doing so. All that the authorities had to do to stop this was go to the correct grave themselves and produce the body. However they didn't do this because they couldn't : the tomb was empty and the body wasn't there.
The theory that Jesus merely swooned on the cross and later revived in the tomb is one that clutches at straws. Jesus was definitely dead when he was taken down from the cross : before his crucifixion he had endured a flogging which would have led to appreciable blood loss, and rendered him physically unable to carry the crossbar of his cross, as those sentenced to death were supposed to do. After he had been on the cross for hours, one of the Roman soldiers thrust a spear into Him to make sure that he was dead, and blood and water flowed out. John, one of our eyewitnesses, would never have appreciated the medical significance of this detail : he was simply writing down what he saw. Modern medicine tells us that the 'water' would have been pericardial fluid caused by the spear piercing Jesus' heart. He was definitely dead, a fact confirmed by the four Roman executioners.
Post-Resurrection Appearances
This leads me on to another piece of objective evidence : the post-resurrection appearances of Jesus. He didn't just appear to his disciples after the resurrection : he appeared to a variety of people in a variety of situations. In one of his letters, Paul mentions over five hundred witnesses to a single appearance, most of whom were still alive at the time he was writing. He urged his readers to go and ask all of these people if they still didn't believe what he was telling them. The appearances cannot be explained away as hallucinations, as they happened at different times, to people of all sorts of personality type. The reports of the appearances also stop abruptly, wheseas hallucinations die away slowly. You'll have heard the phrase 'doubting Thomas' : Thomas was a cynic, who refused to believe the reports of the resurrection until he saw Jesus for himself. But when he saw, he believed.
Miracles
Don't let the premise that 'miracles don't happen' blinker you thinking on this matter. How do you know that this is true? The question of the existence of God is outwith the realms of science, and there is nothing to stop the creator of the universe breaking physical laws within it!
In Conclusion
I have done my best to outline the evidence for the resurrection of Jesus Christ. I could have expanded in much more detail, but it's important to leave time for questions. OK, so here are the facts.