The Law is God's commandments recorded in God’s Word. God wants us to obey these commandments so that we may live. The Covenant is God's promises to us. This Covenant is for us to believe and live. It is God's promises.

In Galatians 3:15, Paul used the example of a contract. In God's contract, we have no bargaining power. All the terms and conditions of this contract can only be fulfilled by God. We cannot do anything, but receive it. This is God's covenant with us. This covenant cannot be cancelled out and is a unilateral covenant.

In Galatians 3:16, the doctrine of the seed is important. The word “seed” has a two-fold sense. One refers to a group of people, i.e. Abraham's descendants (c.f. Gal 3:29). Another meaning of “seed” refers to a very special and unique person, i.e. Christ. This “seed” (Christ) was revealed not only in the New Testament, but also in the Old Testament (c.f. Gen 3:15).

In Galatians 3:17-18, we know that the Law (the Ten Commandments) was given by God to Moses 430 years after God gave the promise to Abraham, Isaac and Jacob. Thus, the law does not override the promise given to Abraham and his descendants.

The reason God gave the Law is explained in Galatians 3:19. The Law functions like a mirror. We see our true self when we look at the mirror. Thus, when we read the Ten Commandments, we see our own sinful self. The Law also functions as a rod to correct us (Gal 3:24). And the Law points us to Christ. He is the only One who can save us from our sins.

In Galatians 3:20, we can only be saved through a Mediator, i.e. the Lord Jesus Christ. He mediates between us (the offender) and God (the offended).

In Galatians 3:21-22, although there is the covenantal promise of God, the Law is given to enhance God's promise and also to show how wicked and unworthy we are. So that we will see our need for a Saviour and go to Christ for salvation.

Thus, the Law and the Covenant do not contradict each other. It shows us the only way to salvation, which is by faith in the Lord Jesus Christ.