After citing many examples that show the total depravity of man, Paul uses that to explain a primary purpose of the law to stop every mouth. Because the heart of carnal man is to deny reality because of their sin, God gave the law to stop their mouth and so that they see their sin. There is no law that can save from sin, but God's perfect law makes every man's guilty clear to them. Man wants to think he is righteous and wise, but the law forces him to recognize that he is neither.