This chapter provides a succinct summary of the basic proposition of John’s gospel. In John 20:19, John states a specific reason why he chose to write what he included in his gospel, among the myriad of things he could have written.
Accordingly, John will demonstrate throughout his gospel the starting place for the gospel, to believe Jesus is the Christ, the Son of God, as well as the application of the gospel, to believe in the commands of Jesus, so that we experience the great benefit of the gospel: to experience “life in His name.”
In Chapter 3, John does both. First, he tells us of an interview Jesus had with Nicodemus, and provides a powerful witness for us to believe that Jesus is the Christ, the Son of God. Then he describes an interview between John the Baptist and one of his apparently disgruntled disciples, and provides us with a clear message that those who believe can choose between living in active belief, resting in obedience to Jesus, and experience life, or we can choose the adverse consequences that come from sin. It is a binary choice: life or death.
John makes clear that there is a gift of eternal life to be received by faith, and a great prize of experiencing “life in His name” through the obedience of faith. John gives us this through Jesus’ testimony to a ruler of the Jews, and John the Baptist’s explanation to his apparently disgruntled disciple.