It’s interesting how Peter, James and John react to having witnessed the transfiguration of Jesus in His dazzling glory on the mountain top. And they certainly couldn’t understand what Jesus meant when He talked about “rising from the dead.” They threw around different ideas of what this could mean, all of them over-spiritualised, because they couldn’t get their heads around the possibility that Jesus meant just what He said.
The religious teachers taught that Moses and Elijah would come to earth to announce the coming of the Messiah. These were the two greatest prophets of their religion. But God the Father is displeased when Peter wants to build places of rest for Jesus, Moses, and Elijah. God hides the scene from view and his voice is heard from heaven pointing to His beloved Son, and commanding all to listen only to Him. And then, when the three disciples recovered, Moses and Elijah were gone. They saw Jesus only.
Peter, James and John are part of Jesus’ inner circle, since He makes a point of including them in some very special events. And so they witness Jesus glorified and speaking with Moses and Elijah. We don’t know what they spoke about, but it would have been an incredible conversation to have listened in on.
When Jesus said He was going to Jerusalem, where He would be killed, Peter strongly rebuked Him and wanted to stop Jesus from going because he didn’t fully understand the purpose of Jesus’ mission. And Jesus, in turn, has rebuked Peter for standing in His way with his worldly thinking and lack of spiritual understanding. Jesus wants to explain to His disciples the real purpose of His mission and why He must go to Jerusalem and the cross.