Why Works?

Galatians 3:19-20    
19 What purpose then does the law serve? It was added because of transgressions, till the Seed should come to whom the promise was made; and it was appointed through angels by the hand of a mediator. 20 Now a mediator does not mediate for one only, but God is one.

The Law of God was given as an addition to the promise to Abraham 430 years earlier.  It was given because man’s sin needed to be shown by our failure to obey God in doing good over evil, and the Law pointed out the transgressions in our breaking of it.  The promise was still a covenant in effect, so the one to whom it would rest on and be ministered through was God’s Seed, His chosen or anointed one (Messiah).  He would meditate this covenant of faith with Abraham to His people from all nations, standing between us and God as the sole mediator able to do so.  The people of God “received the law by the direction of angels and have not kept it.” (Acts 7:53).  None of us can keep the Law completely and from the heart, and this is why it was given to make that clear, and to point us back to the promise by faith.  This is the gospel, that God’s grace by faith in Christ’s work did what our work never could.