From his prologue to his epilogue, John sets out to answer two primary questions: “Who is Jesus?” and “What has Jesus come into this world to accomplish?” John fixes our eyes on Jesus himself, the very embodiment of the gospel. John begins his Gospel heralding the advent of the new creation story—positioning Jesus as the principal character and carrier of the whole narrative.
Unlike the other three Gospel writers (Matthew, Mark, and Luke), John did not structure his Gospel with a strict chronology in mind. His is both a selective and a strategic record. In fact, while all four Gospel writers focus their accounts ultimately on the death and resurrection of Jesus, John spends a full 40 percent of his account on this last week—the most crucial week of our Lord’s life and of human history (John 12:1–20:25). Everything John tells us about Jesus leads us to his cross and his empty tomb—to his substitutionary death and glorious resurrection.
We don’t have to guess about John’s purpose and goal in writing his Gospel. John tells us that he chose particular stories and “signs” so that “you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name” (20:30–31).
Who is Jesus? He is the promised Messiah. Why did he come? Jesus has come to give us life—abundant life (10:10), eternal life, the life of “the age to come” (cf. Luke 18:30; Heb. 6:5). The gospel of God’s grace is so much more than a story about life after death. It is also a story about life before death—how through Jesus’ death and resurrection the kingdom of God has already arrived and has restored fallen creatures, and the fallen creation, to their right relationship with the Lord of life. And one day this kingdom will arrive in fullness, eradicating all remaining sin and sadness." From the ESV Gospel Transformation Study Bible