The Gospel book splits into two halves. Chapters 1–11 narrate seven miracles of Jesus that John calls “signs.” Each sign signifies that Jesus does the works of the Father so that readers might identify the Son with the Father (John 10:37–38).
The Gospel of John aims to persuade readers that “Jesus is the Christ, the Son of God, and that by believing you may have life in his name” (John 20:31).
The means by which the Gospel communicates its purpose is eye-witness testimony. The evangelist identifies himself as “the disciple who is bearing witness about these things, and who has written these things, and we know that his testimony is true” (John 21:24).
Putting the purpose and mode of delivery together, we can say that John as an eyewitness of Jesus Christ carefully selected and organized his Gospel book so that readers would believe and have life in the name of Jesus, the Christ and the Son of God.