All of us ought to be constantly reminded that it is the purpose of the gospel writers not just to put down a record of what they had come to know about Jesus, but to put that record down in such a way that it was persuasive to the reader. No doubt the writer of the fourth gospel best summed up their purpose when he wrote:
Now Jesus did many other signs in the presence of the disciples, which are not written in this book; but these are written that you may believe that Jesus is the Christ; the Son of God, and that believing you may have life in his name.John 20:30-31