The religious leaders had missed the whole purpose of the law. It was given to show us our sins and to bring us to our knees before God. The Law humbled the heart of any who could hear God.
Instead of being humbled before God at their inability to keep the Law, the religious leaders became proud that they were chosen from all the tribes on earth to receive the Law. They seemed to think that by God giving them the Law, they became better than the other nations around them.
They became authorities about God's Word, adding their own thinking to the Law. They changed it by what they added, developing it into a system of self- righteousness. Then they oppressed those who did not practice their system.
In the same way today, men are adding their own thinking to Gods Word. They ridicule others who don't see it according to their man-made systems, and they forget that God's Spirit is our only real teacher.