John, most scholars believe, was written later than the other gospels and I believe that John had a specific aim in mind when it came to writing this Gospel. I believe his aim was to disclose fully, who Jesus Christ is. In those days there were already some who questioned whether Jesus was a man or whether he was God. Some said that he could not have been a man and others said that he was only a man.
2 Timothy 3: 16-17
All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the servant of God may be thoroughly equipped for every good work.