“For by the works of the Law no human being will be justified in his sight, since through the Law comes knowledge of sin.”
If the Law does not save us why have it? Because it provides us with an important thing needed for a relationship with God—an awareness that our relationship has been broken through our rebellion. We cannot seek or obtain something if we do not know we need it. A person must feel a conviction of sin in order to ask God for forgiveness.
It is not enough to know there is a God, that He has created us for a relationship with Him, and that He has provided a means for that relationship to exist. We must recognize that we have personally separated ourselves from God and need to have our relationship repaired.
Without the Law we do not readily see that we have sinned, and without an awareness of sin we cannot repent, and without repentance we cannot be saved. So the Law is a good and helpful thing, it just does not get people back into a relationship with God.
So now we have seen two important concepts in Paul’s treatment of the Gospel: Sin and the Law. Sin separates us from the Creator. It is our rebellion and it is something in which every single human being in space and time has been engaged. The Law shows us that we are in rebellion. Even the people who instinctively know right from wrong do wrong. Even people who know what God wants by means of the Law do wrong. Every person who has ever lived has rebelled against God and has severed their relationship with Him.
This is the extent of our problem, but God has a solution…