The greatest myths surrounding Christ were promulgated by the Pharisees and Sadducees, who, on false testimony had conspired (although they did not get along) to arrest Jesus Christ and have him executed, with trumped up charges; and even these charges were not worthy of death. By killing Jesus, they hoped that the threat that he posed to their power (and glory) would be done away with. To ensure he stayed dead and in the grave they managed to convince the Romans to place military personal at the tomb, which was sealed. Matthew 27:62 - 64 indicates the concern of the Pharisees and Sadducees, and the securing of the tomb.
One also presumes that Pilate had had enough of the Jews. Scripture indicates that Pilate's wife was troubled by the events and had warned Pilate about doing anything to the ‘innocent man' (Matthew 27:19). The earthquakes and blackness must have surely disturbed his wife if not Pilate himself. Pilate therefore allowed the Jews to use Roman soldiers as guards at the tomb and with the tomb sealed. The seal indicated the authority by which it was sealed - only an authorised Roman could break the seal, and if not authorised, the death sentence could be applied.
The empty grave posed a huge problem for the Pharisees and Sadducees - it is well recorded that the body was not snatched away as the tomb stone was large and heavy and the Roman soldiers would have been themselves executed if they had left the tomb unguarded (falling asleep at one's post was a death sentence) - Jesus was a criminal and could not be allowed to escape - although they had murdered him! What is interesting is the response - not retribution on the guards, but rather a paying-off, of them:
“Now while they were going, behold, some of the guard came into the city and reported to the chief priests all the things that had happened. When they had assembled with the elders and consulted together, they gave a large sum of money to the soldiers, saying, "Tell them, 'His disciples came at night and stole Him away while we slept.' And if this comes to the governor's ears, we will appease him and make you secure." So they took the money and did as they were instructed; and this saying is commonly reported among the Jews until this day. Matthew 28:11-15 NKJV
The supernaturally opening of the tomb serves to indicate that Christ did rise again - Jesus' body did not end in the tomb and humans could not prevent him from rising.
Who is he who condemns? It is Christ who died, and furthermore is also risen, who is even at the right hand of God, who also makes intercession for us. Romans 8:34 NKJV
There were many witnesses to the resurrection - various women met the angels who had opened the tomb to allow all so see that Christ had risen. Note that the tomb did not need to be opened for Christ to rise - the open tomb was for us to look in - proof of his resurrection.
Roman crucifixion did not result in live people being taken down from the cross. They were always dead - left to die or hasten to die by having they long bones broken so they could not relieve the pressure on their chest cavity in order to breath. Christ had been so beaten-up prior to crucifixion by being flogged with a steel whip (scourged) and then during crucifixion he had his belly opened up with a spear, which would have damaged many of his gut organs - for both water and blood was seen to flow from the body - it is inconceivable that he could have been taken down from the cross half dead, then a day or so later walking away from the tomb! The myth that somehow he survived is unbelievable and without merit.
One explanation is that everyone went to the wrong tomb - yet the tomb was a private tomb in a private garden owned by Joseph of Arimathea - whose whereabouts was exceedingly clear - since the Roman soldiers, Mary Magdalene, Peter, John and the other women had all been to the tomb. It could also be speculated that the Pharisees had also inspected the tomb but certainly one or more ranking Roman officials had visited the tomb to place their seal on it. No! The tomb was easy to find - on the grounds belonging to Joseph of Arimathea.
The best defence by the Jews and Romans in their argument that Jesus had not risen was to open the tomb and show the body. Of course they could not to do this because Jesus had risen! The power of his resurrection was seen within a few months in Jerusalem:
"Men of Israel, hear these words: Jesus of Nazareth, a Man attested by God to you by miracles, wonders, and signs which God did through Him in your midst, as you yourselves also know--Him, being delivered by the determined purpose and foreknowledge of God, you have taken by lawless hands, have crucified, and put to death; whom God raised up, having loosed the pains of death, because it was not possible that He should be held by it. Acts 2:22-24 NKJV
And with many other words he testified and exhorted them, saying, "Be saved from this perverse generation." Then those who gladly received his word were baptized; and that day about three thousand souls were added to them. Acts 2:40-41 NKJV
And with great power the apostles gave witness to the resurrection of the Lord Jesus. And great grace was upon them all. Acts 4:33 NKJV
On at least twelve separate occasions Jesus Christ was seen after rising from the tomb. Mary Magdalene (John 20:11-18; Mark 16:9); the other women (Matthew 28:8-10); Peter (Luke 24:34); the two disciples on the road to Emmaus (Luke 24:13-35); ten of the disciples (Luke 24:36-43; John 20:19-24); Thomas especially (John 20:26-29) and all eleven disciples, eight days later (John 20:24-29); seven disciples by the Sea of Tiberius (John 21:1-23); to five hundred at one time (1 Corinthians 15:6); to James (1 Corinthians 15:7); to all eleven apostles, and others, at the ascension (Acts 1:3-12). Later Paul (Acts 9:3-8) saw Christ, as did Stephen (Acts 6:5-9); and the Apostle John (Revelation 1:12-18). In every case they saw Jesus Christ on bodily form, raised from the dead. Thomas was shown the scars to prove it was indeed Christ.
The disciples, all of whom forsook Jesus at the cross, became the founding leaders of the Church - which has changed the world, in face of extreme persecution. They had nothing to gain if Christ had not risen in placing themselves in opposition to the Jews, Greeks and Romans; proclaiming the “good news“ which resulted in their martyrdom. Who would promulgate a lie and be killed for it? On the other hand Scripture shows that Jesus appeared to about 500 people in the 50 days between death & resurrection and when he ascended into heaven.
To suggest that the disciples had stolen the body is illogical - a dead Christ serves no purpose. The disciples could not proclaim the gospel without Christ rising. So the myth that they stole the body is without merit. Overall there was a remarkable transformation of these disciples. They became bold, faithful and determined to promulgate the new covenant in the face of death.
The entire world has been affected by the Messiah dying for the sins of the world and rising again. It changed history, it created ‘Sunday', and transformed our attitude to other humans - “love your neighbour“ - no-longer would the world think of some humans as being subclasses (albeit it took rather a long time to top slavery). As the Jews new full well - if this was a fairy tale it would go away and only be studied in academic circles as another myth, but if this was the word of God nothing could stop it:
Then one in the council stood up, a Pharisee named Gamaliel, a teacher of the law held in respect by all the people, and commanded them to put the apostles outside for a little while. And he said to them: Men of Israel take heed to yourselves what you intend to do regarding these men. For some time ago Theudas rose up, claiming to be somebody. A number of men, about four hundred, joined him. He was slain, and all who obeyed him were scattered and came to nothing. After this man, Judas of Galilee rose up in the days of the census, and drew away many people after him. He also perished, and all who obeyed him were dispersed. And now I say to you, keep away from these men and let them alone; for if this plan or this work is of men, it will come to nothing ; but if it is of God, you cannot overthrow it--lest you even be found to fight against God. " Acts 5:34-39 NKJV