When he had risen, early on the first day of the week, he appeared first to Mary Magdalene, out of whom he had driven seven demons. She went and told his companions who were mourning and weeping. When they heard that he was alive and had been seen by her, they did not believe. After this he appeared in another form to two of them walking along on their way to the country. They returned and told the others; but they did not believe them either. (But) later, as the eleven were at table, he appeared to them and rebuked them for their unbelief and hardness of heart because they had not believed those who saw him after he had been raised. He said to them, "Go into the whole world and proclaim the gospel to every creature. (Mk 16, 9-15)
This is a summary statement of what had taken place after the resurrection until the beginning of the ministry.
The summary statement gives the real situation among the disciples. The situation was that, the resurrected Jesus appeared to the disciples individually and in groups. But the disciples did not believe the witnesses of the people who had seen the risen Lord. They did not believe in the witness of Mary Magdalene and the two disciples of Emmaus. Was it due to the disbelief among themselves on each other? Jesus also rebuked them for their disbelief and hardness of heart.
Probably the disciples wanted to have a personal experience for themselves. Each one wanted to witness the risen Lord personally. When he met them as a group he did not show them any signs of resurrection or any proof for resurrection. He should have done it because they did not believe the witnesses of the disciples who had seen him earlier.
The only proof or sign of resurrection that Jesus gives is the mission to be accomplished. The mission is to proclaim the gospel to all creatures. Fulfilling of the mission gives them the belief in the resurrection. Proclaiming the gospel is the belief in the resurrection.
…Simon Peter said to them, "I am going fishing." They said to him, "We also will come with you." So they went out and got into the boat, but that night they caught nothing. When it was already dawn, Jesus was standing on the shore; but the disciples did not realize that it was Jesus. Jesus said to them, "Children, have you caught anything to eat?" They answered him, "No." So he said to them, "Cast the net over the right side of the boat and you will find something." So they cast it, and were not able to pull it in because of the number of fish. So the disciple whom Jesus loved said to Peter, "It is the Lord."…
So Simon Peter went over and dragged the net ashore full of one hundred fifty-three large fish. Even though there were so many, the net was not torn…
… because they realized it was the Lord. (Jn 21, 1-14)
When Jesus was standing on the shore the disciples did not realize that it was Jesus. It is strange. They had lived with him right through his time of public ministry. They were his close friends, yet they did not realize that it was Jesus. Was it because they did not expect him there? Or, were they not convinced that he was raised from the dead? Or were they ready to go back to their original life style?
Jesus told them to cast the net over the right side of the boat. They obeyed him and there was a big catch. This miracle should have had a message for the disciples. Jesus who had asked them to leave the boats and nets to follow him; and he in stead would make them fishers of men, now asked them to cast the net. There were one hundred and fifty three large fish in the net. There is a traditional interpretation which says that, at the time of Jesus, the Jews believed that there were only 153 types of fish in the sea. So the net that was cast by the disciples at the command of Jesus got all types of fish.
So the message could be that the mission given to the disciples in the world (sea) would hold all types of people. The kingdom (net) would drag in all types of people. This miracle (turned) message is equal to the synoptic saying: go and preach to the whole world etc.
When the mission is given to them, then the disciples realized that it was the Lord.