After the resurrection, Jesus did not go back to his father right away. Instead, he chose to stay on the earth for 40 days. During this period, he came to visit his disciples. Why?
First of all, he came for peace. At that time, the disciples were afraid of Jews who arrested and killed Jesus. It seems the fear came from outside. However, the basic reason of their fear is that they lost their faith in Jesus and they forgot who Jesus was. Even though Jesus already told them he would rise again and a few women and disciples met risen Jesus, it is really hard to believe that Jesus would resurrect. Therefore, Jesus came to give them peace by proving his resurrection.
Moreover, Jesus came to send his disciples to the world. They were there already, yet they were not aware that they were sent. Jesus said, 'As the Father has sent me, I am sending you.' Jesus was sent so he lived according to the will of the one who sent him. Now Jesus is sending them, which means they were supposed to live by the will of Jesus. As the disciples of Jesus, we are sent by Jesus, so we are to live by his will. How do we know it? Through his words and prayer. If we live like this, we can have unshakable hope, because our citizenship is in heaven, and we live in heaven by standing on the earth. And this hope allows us to be strong in afflictions.
Another reason Jesus came to visit is to give them Holy Spirit, the third person of the Trinity. Jesus promised that he would be with them always, and to accomplish his promise Holy Spirit comes and dwells in all Christians at the same time. And verse 23 talks about the church's authority. With Holy Spirit and church, all his disciples were able to keep the sense that they were sent and lived out by the will of Jesus. Now that same job remains in us. Let us follow their footsteps!