John’s Gospel contains unique material about Jesus’s life and ministry while omitting other aspects of it that Matthew, Mark, and Luke include. For example, John has no account of the birth, baptism, or temptation of Jesus.
John introduces Jesus Christ to the world by linking Him to the Logos, which was a Greek concept that connected with the most sophisticated philosophical thinkers in the first century. John opens with a flashback to Genesis and the creation story by saying, “In the beginning was the Word” (1:1).
John states his purpose at the end of the book. “But these are written 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” (20:31).