As an opening thread, I would like to offer a scenario of the circumstances around the first Easter. I think it fits the evidence (which is not the same as fitting the Biblical texts, but rather explains why they say what they say). It does allow that the resurrection did happen, so is not exactly my position. I think this better fits the evidence than the usual Christian story. I invite you lot to shoot it down...
When Jesus was arrested, the disciples fled Jerusalem for fear of being arrested themselves (Mark 14:27). Jesus was tried for sedition - claiming to be the Messiah, the king of the Jews, was evidence enough for the Romans, and crucified. He was buried with the other criminals (Acts 13:29 indicates the enemies of Jesus buried him), his body forgotten about. Peter and others resumed their careers as fishermen in Galilee (John 21:3). Some days or weeks later, the disciples saw the resurrected Jesus in Galilee (Mark 14:28, Mark 16:7). They saw a bright light (Acts 9:3), all that could be seen of his new, heavenly body (1 Cor 15:42-49).
The very early church did not care about the old body; Jesus had cast it off, and appeared in his new heavenly body. They looked at scripture to guide them, and determined that Jesus must have been resurrected on the third day from Hosea 6:2.
While they may have expected a bodily resurrection, what they saw convinced them otherwise. Remember how dramatic Paul's conversion was; if the disciples saw something similar, I think it reasonable to suppose they would modify their beliefs. Also bear in mind that they were not expecting the messiah to be God incarnate, but somehow (and at some later point) they became convinced of that. People's theologies do change!
So these were the events the started a new religion. This fits what Paul states in 1 Cor 15:
1 Cor 15:3 For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, 4 and that He was buried, and that He was raised on the third day according to the Scriptures, 5 and that He appeared to Cephas, then to the twelve. 6 After that He appeared to more than five hundred brethren at one time, most of whom remain until now, but some have fallen asleep; 7 then He appeared to [c]James, then to all the apostles; 8 and last of all, as [d]to one untimely born, He appeared to me also.
Over time, people started to fill in the gaps. No one knew what had happened at the trial or crucifixion, but they knew about the Roman's procedures, so they could have a good guess. The Romans were known to allow the dead to be removed according to Jewish law, so it was reasonable to suppose that happened to Jesus, and sounded better than saying he weas left up there for the crows. After a few decades, the story got more developed, with Jesus put in a special tomb, and later still the story that the tomb was found empty was added.
This then was the PMPN that Mark based his gospel account on.
The guards on the tomb were a later addition to counter claims the body had been stolen. Jesus eating fish were a later addition to counter claims Jesus was merely a ghost, as was Thomas inspecting the crucifixion imprints. Other later additions include all the post-resurreection sights in and around Jerusalem, Joseph of Arimathea being a Christian and the dead saints walking around Jerusalem.
I can envisage a cry of "cherry picking" regarding the verses I cite. However I suggest that these verses are harking back to the original story. For example, Jesus predicted the disciples would scatter; that was in the original text, and was left in even after the narrative changed to say that the disciples remained in Jerusalem. Another example is the final chapter of John stating the disciples became fisherman again. Why would they do that if they had been told by the resurrected Christ to spread the gospel? They would not. The account comes from a much earlier tradition in which the disciples resumed their old lives before seeing Jesus resurrected.
I do not think we can know what actually happened. All I claim is that this fits the evidence better than the usual Christian scenario.