What was the Law given for?
The Law was given for one purpose: to show mankind how far they fell short of God's standard, because no one could keep the Ten Commandments. It stops every mouth and makes all the world guilty before God, so that by the Law no flesh can be justified; it gives only the knowledge of sin.
Les explains that only Israel was placed under the Law, yet its convicting power extended to the whole human race, stopping every mouth and making all the world guilty before God, as Galatians chapter 3 states. He contrasts the common misconception that the Law was given to help people do right and earn God's wink of approval. Instead, the Law was given for one purpose: to show mankind how far they fell short of God's standard, since no one has ever been able to keep the Ten Commandments. Verse 20 declares that by the deeds of the Law no flesh can be justified; the Law gives only the knowledge of sin. Les teaches that the Law can do nothing but convict a person of utter sinfulness, and that is why it was added. Up until that time, God could not impute all the wickedness before the Flood or put it to those people's account.