Summary: In the days following his resurrection Jesus keeps appearing, eventually over 500 people are witnesses that he is alive. However the most important witness to the resurrection is that all Scripture points to the suffering, but risen, Saviour.
You can listen to the full message here:
Our King Jesus Proves He Is Alive
When it comes to the importance of the resurrection Paul pulls no punches
14 If Christ has not been raised, our preaching is useless and so is your faith.
… 17 If Christ has not been raised, your faith is futile; you are still in your sins. 18 Then those also who have fallen asleep in Christ are lost. 19 If only for this life we have hope in Christ, we are of all people most to be pitied.
1 Corinthians 15:14, 17-19
No resurrection means no hope and no eternal life.
So how can we be sure that Jesus rose from the dead?
Firstly we have from Scripture an extensive list of people who saw the risen Lord.
I’ve brought all of the texts together so that you can see how extensive the testimony is. I’ve tried to put them in a bit of chronological order.
5 The angel said to the women … 6 Jesus is not here; he has risen, just as he said.
14 At this, (Mary) turned around and saw Jesus standing there, but she did not realize that it was Jesus.
8 So (Mary Magdalene and the other Mary) hurried away from the tomb, afraid yet filled with joy, and ran to tell his disciples. 9 Suddenly Jesus met them. “Greetings,” he said. They came to him, clasped his feet and worshiped him.
13 Now that same day two of them were going to a village called Emmaus, about seven miles from Jerusalem … 15 As they talked and discussed these things with each other, Jesus himself came up and walked along with them.
33 They got up and returned at once to Jerusalem. There they found the Eleven and those with them, assembled together 34 and saying, “It is true! The Lord has risen and has appeared to Simon.” 35 Then the two told what had happened on the way, and how Jesus was recognized by them when he broke the bread. 36 While they were still talking about this, Jesus himself stood among them and said to them, “Peace be with you.”
Luke 24: 33, 36
19 On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jewish leaders, Jesus came and stood among them and said, “Peace be with you!”
26 A week later his disciples were in the house again, and Thomas was with them. Though the doors were locked, Jesus came and stood among them and said, “Peace be with you!”
1 Afterward Jesus appeared again to his disciples, by the Sea of Galilee. It happened this way: 2 Simon Peter, Thomas (also known as Didymus), Nathanael from Cana in Galilee, the sons of Zebedee, and two other disciples were together.
16 Then the eleven disciples went to Galilee, to the mountain where Jesus had told them to go. 17 When they saw him, they worshiped him; but some doubted.
5 Jesus appeared to Cephas, and then to the Twelve. 6 After that, he appeared to more than five hundred of the brothers and sisters at the same time, most of whom are still living, though some have fallen asleep. 7 Then he appeared to James, then to all the apostles, 8 and last of all he appeared to me also, as to one abnormally born.