John 20

1 After the Passover, on Sunday morning, Mary Magdalene was the first to the tomb. The other Gospels record that she and the other women were to meet there to finish embalming Jesus' body. No one visited the tomb during the Passover or the Sabbath because God had said that no one should work on these holy days. Since the days were measured from sunrise to sunrise, Mary began her journey to the tomb at the first hint of sunlight, so it was still dark when she arrived.

John's Gospel does not mention the guards or the angels at the tomb.

2 Mary naturally assumed that someone had taken Jesus' body. While the other Gospels tell of angels delivering the good news of Jesus' resurrection, these appear to have occurred after this event.

Mary uses the term "we" indicating that at least one other person with her had seen the open tomb.

5 John waits for Peter, not knowing what he should do.
6 Peter does not hesitate, but enters the tomb to investigate.
7 If someone had taken the body, it would be unusual for them to have left the linen wrappings behind. John makes a point of mentioning the head wrapping, which apparently had been painstakingly folded and placed somewhere away from the linen cloths.
8 Finally, John enters the tomb to look. He says that he "believed" at that moment. It is implied that he at least had some thought that Jesus may have indeed escaped death.
11 While John and Peter left to ponder these things alone, Mary remained at the tomb at a loss as to what to do. Finally, she decides to look inside the tomb herself.
12 Mary's apparent lack of surprise or fear indicates that she did not recognize the men as angels at the time.
13 People mourn to help cope with the death of a loved one. It is usually easiest to accept the death when the body is viewed. Mary no longer had a body to mourn over, so she did not know how she would find closure in this matter.
14 Not waiting for any explanation, she turns her back on the angels to leave. In so doing, she sees Jesus, but did not recognize Him at first.
15 Mary is still assuming that someone moved Jesus' body. If by some chance this man took the body and was willing to tell her where it was, she would return it to the tomb.
16 Hearing her name in a familiar voice, she finally recognizes Jesus. She had been looking for Jesus' dead body to mourn over, but she found Him alive and rejoiced.
17 Mary was apparently holding tightly to Jesus. Jesus asks her to let go because He has much to do in the time between now and His ascension. He does ask her to go and tell the others that He is alive.

This is Jesus' first appearance after His resurrection (Mark 16:9). Jesus first appears to a woman, which is significant because women had less social status during that time. Every person, regardless of social status, has an equal need for Jesus.

18 Mary relates the news to the disciples with much enthusiasm. However, the disciples are not moved enough to go and investigate for themselves.
19 Jesus now visits the disciples. Though the doors are locked, Jesus appears in their midst. Jesus' new body is not restricted by physical barriers. The other Gospels tell of the disciple's fear. Jesus assures them that there is no need to fear His sudden appearance.
20 To confirm His identify, Jesus showed the disciples the marks of His death on the cross. Jesus now had an immortal body, but the scars from the mortal body remained.
21 Now that Jesus had calmed their immediate fear, He wanted to calm their long-term fear of the Jews. They would not be effective if they continued to hide from the Jewish rulers. Instead, they were to go out and preach.
22 This may be an "infusion" of the Holy Spirit that would sustain them until the permanent indwelling occurred at Pentecost. Jesus may have breathed on them to help them to receive the Holy Spirit later. The act of breathing on them appears to be a parallel for God breathing life into Adam. This may be the point where the disciples were "born again," as Jesus created new life in them (although some feel that John 15:3 may mean that the disciples were already born again).
23 This sounds similar to what Jesus said to Peter in Mat 16:19. According to the Adult Teacher's Guide, The Greek wording of this verse is unusual. It conveys the idea that the disciples can confirm that God has forgiven a believer, rather than invoke spiritual forgiveness themselves. Likewise, a disciple can confirm that a person who does not believe the Good News of Jesus is not forgiven their sins.
24 For some reason, Thomas was not with them.
25 This is the origin of the idiom "doubting Thomas." Thomas had the testimony of more than a dozen friends and companions, but he would not believe that Jesus was alive. He demanded not only to see Jesus, but also to touch the wounds that the others claim to have seen.
26 Even after a week of testimony and joy expressed by the others, Thomas remained an unbeliever in their midst. This could have caused some tension, since Thomas indirectly calls them liars by his unbelief.

Then, unexpectedly, Jesus again appears to all of them while they are locked in the room. Again, He assures them that they should not be afraid (probably Thomas most of all).

27 Next, Jesus speaks directly to Thomas. He knows exactly what evidence Thomas had asked for, although no one had the opportunity to tell Jesus. Jesus chides Thomas for his unbelief.
28 It is not said that Thomas actually felt the need to touch Jesus: the sight may have been enough. He declares Jesus not only to be Lord, but God. Thomas correctly surmises that no one else but God could accomplish the resurrection.
29 For an unbeliever, Thomas was in the fortunate place to see the resurrected Jesus. However, the many millions of Christians who would believe later would not have the benefit of seeing Jesus physically during their lifetime. Instead, their faith would be based on the testimony of others and the books that would eventually make up the Bible. Indeed, Thomas was saved by his faith after seeing physical evidence, but it is even a greater accomplishment for one to find faith with "only" the historical and spiritual evidence.

There are many who refuse to believe until all the evidence is before them and explained to the smallest detail. Sadly, they ask for something they will not receive until Judgement Day, which will be too late to make a decision. Like the religious leaders of Jesus' day, no matter how much evidence is given, they continue to demand more. God is not on trial, and He is not obligated to produce any more evidence than He already has. The evidence He has provided is enough for a reasonable person to make an informed decision about Jesus.

30 In an aside, John explains that his book is a summary of what Jesus did (see also John 21:25).
31 He chose the material that would best help the reader understand the Jesus was the Messiah and the Son of God. His ultimate purpose is to present enough evidence to convince someone to believe in Jesus and gain eternal life with God through faith in Him.