Paul now takes up another aspect of God's dealings with Abraham and refers to the covenant which God made with him and which was an absolute pledge that his promises would be fulfilled. The Law, which was given long after God made his covenant with Abraham, did not cancel anything God had promised. God's promise was fulfilled in the descendant of Abraham, Jesus Christ. The fulfillment of God's promise did not depend in any way on the Law. Paul then asks a question which the Galatians must also have been asking at this point. What was the purpose of the Law?

Paul replies that it was intended to show what wrongdoing was, to make people aware of the terrible nature of sin, and it was meant to last until the descendant of Abraham, Jesus Christ, came. In Paul's thought here is the idea that a person cannot feel the need to be saved from sin until he knows what sin is. The Law prepared the Jews for the coming of Jesus Christ, Mediator between God and man, making the Jews aware of their separation from God, so that they might be ready for the new revelation.