A correct understanding of the Covenants is vital to a correct understanding of the Gospel of Jesus. The new Covenant is God's one-way-promise to us whereas the Old Covenant is the people's promise to do only what God is capable of doing. This Old Covenant is worthless and leads to only death. Man cannot fulfill God's promise - only God can.
Many rebel against the idea that ALL must be received as a gift; our efforts do not contribute one iota towards our salvation.