JESUS HAD NOT been through rabbinic training, and it would not be expected that he could sustain a continuing argument from Scripture…
It was this that seems to have astonished his hearers. They would not have expected a man who came from a carpenter’s home in Nazareth to have been able to teach like Jesus taught.
This is a fine piece of Johannine irony. He made it clear at the beginning of the Gospel that Jesus is the divine Logos, the Word of God. Now he sees the Jews confronted by the Logos incarnate and calling him “this uneducated fellow.” They could not recognize the divine wisdom when they heard it. Leon Morris, “Reflections on the Gospel of John,” 261
“Now about the middle of the feast Jesus went up into the temple and taught. And the Jews marveled, saying, ‘How does this Man know letters, having never studied?’ Jesus answered them and said, ‘My doctrine is not Mine, but His who sent Me.'” John 7:14-16
Mike Benson