And when Jesus finished these sayings, the crowds were astonished at his teaching, for he was teaching them as one who had authority, and not as their scribes.
People noticed a difference in the way that Jesus taught. He taught as one who had authority because He was the authority. He spoke the very words of God, rather than offering commentary on the scriptures. He was convincing because He was the truth. And He got to the heart of the matter over and over again in the Sermon on the Mount. At every level, He superceded the mere thoughts of men that so characterized the legalism and barren teaching of His day.
Jesus is always challenging because He teaches with authority. When I am confronted by my sins and my less than holy view of the world, it is because Jesus is Lord. In fact, I find it interesting that Jesus ends His sermon with warnings against false teachers, false professors of Him, and false foundations to life. He makes it clear that a spiritual pursuit is not enough. Those Who want to find eternal life, and God's approval, must build their lives on Jesus and His position as Lord. They must not just profess Him, but possess Him. They cannot just say they obey. They MUST do the will of the Father.
I want my life to bear good fruit. I want to obey my Lord. I want my life to be the house that is built on the Rock. And I am astonished at the teaching of my Lord. It is as true and powerfully disturbing today as it was on the hillside in Palestine so long ago. The authority of my Lord over my life, and my thoughts and plans, is absolute. And that authority must compel me to live differently and do the will of the Father.