Q. I would like to know why God gave the Law. Up to the time of Moses, people had a relationship built on faith. Other than the conclusion, “the law is to show up your sinful nature” why do you think God gave the Law?
A. In Romans 3:20 Paul said, “Therefore no one will be declared righteous in his sight by observing the law; rather, through the law we become conscious of sin.” Without the standard provided by the Law there’s no way to tell what is sin and what is not, just like without a posted speed limit there’s no way to tell what is speeding and what is not.
When Jesus clarified the requirements of the law in Matt. 5-6, He showed that God’s standards are so high that even the Pharisees, who were obsessive about keeping the law, could not hope to achieve the righteousness God requires (Matt. 5:20). His purpose was to demonstrate man’s inescapable need for a Savior.
In summary the Law was given to quantify God’s requirements for righteousness, so we would know what He expects, and to convince us that without a Savior we can never meet His requirements.