This begins with the philosophical introduction, where John emphasizes that Jesus existed from the beginning of God's creation; in fact, somehow Jesus was part of God. This emphasis on Jesus' divinity occurs repeatedly in John, usually through "I AM" statements, such as "I am the bread of life" or "I am the resurrection and the life." With the words "I am" Jesus is speaking the exact words (at least as they are translated into Greek) as God spoke to Moses out of the burning bush --usually translated "I am that I am."
John encourages people to see that Jesus is really God on earth. In fact, Jesus himself gives this invitation several times, telling people to "come and see." If people can see Jesus as someone doing great things, and offering great teaching, with God's authority, then they can believe in the promise of Jesus to be "the resurrection and the life." In some ways, seeing is believing. If people can gain this spiritual sight, they can become faithful disciples; if not, they will remain blind to the promise of Jesus.