Teaching is Not Enough

Jesus is the greatest teacher who ever lives, and I'm not referring to clear communication. Of course I think he is a good communicator, far better than some preachers I've heard. But I refer to the content and authority of his teaching; no man ever spake like this man. Everyone marveled at his teaching for he taught them as one having authority, and not as their scribes.
In a sense Jesus brought nothing new in his teaching. I've told you before there is ethical continuity between old and new testaments. The morality of the old is identical to the morality of the new, and so Jesus brought nothing new in that sense.
Nor is the theology any different. We serve an immutable God, who does not change, and so we must expect unity of theology between the testaments.
What was new in Jesus' teaching was the system updates. With the coming of Jesus the kingdom of God began its official invasion into the world, and that was certainly new. The OT predicted the kingdom of God; Jesus fulfilled that prediction, or part of it.
And Jesus brought new revelations about the kingdom, things which had been kept hidden since the foundation of the world. For example, no one knew the kingdom would come before it comes; Jesus taught that before the final end of time the kingdom breaks into the middle of history to gather disciples for eternal life.