The law of God, centered in the Ten Commandments, is "holy, and just, and good" (Romans 7:12) and expresses perfectly the will of God for holy living. "The man that doeth them shall live in them" (Galatians 3:12).
The problem is that no man can possibly do them all. A man may keep most of the commandments most of the time, but he will inevitably fail in some of them some of the time. Since the law is a divine unit, breaking any commandment--as our text reminds us--breaks the whole law, bringing the guilty one under God's curse of death. "Cursed is every one that continueth not in all things which are written in the book of the law to do them" (Galatians 3:10). "Therefore by the deeds of the law there shall no flesh be justified in his sight" (Romans 3:20).
All men, having sinned against God's law, are therefore lost and in urgent need of salvation. This is where God's wonderful grace comes in. "But now the righteousness of God without the law is manifested, . . . Even the righteousness . . . which is by faith of Jesus Christ unto all and upon all them that believe" (Romans 3:21-22), "Christ hath redeemed us from the curse of the law, being made a curse for us" (Galatians 3:13). He kept the law for us, and bore its curse for us: Thus we are saved through trusting Him.
"What shall we say then? Shall we continue in sin, that grace may abound? God forbid" (Romans 6:1-2). We now desire to keep His commandments, because we love Him. "For this is the love of God, that we keep his commandments: and his commandments are not grievous" (1 John 5:3). We are now able to keep them, because His Spirit now lives in us, and we are "strengthened with might by his Spirit in the inner man" (Ephesians 3:16). HMM