1. The law shows us our sins: "Therefore no one will be declared righteous in God’s sight by the works of the law; rather, through the law we become conscious of our sin." -Romans 3:20-

Even the Gentiles cannot work out for their justification before God. Doing good in not the way of gaining eternal life of being right with God.

2. The law shows us the need for the Savior: "But now apart from the law the righteousness of God has been made known, to which the Law and the Prophets testify (Romans 3:21, NIV)."

Both the work of the law in the Jews and the law in the conscious of the Gentiles shows that people have sinned against God and they need the Savior to save them from the wrath of God which is made clear in their condemnation seen in their conscious (for the gentiles) written in the Scripture and seen in their conscious (for the Jews)

3. Until we know the details around our wrong doing we cannot see the need for being saved or asking for mercy from God.

4. It will be difficulty to understand the doctrine of justification and its implications: the idea of the righteousness of Christ accounted to the sinner by faith can be grasped well within the framework of the law operating as the convicting and condemning one.