Romans 3 teaches us that law tells us our duty, that is, what we are obliged to do. It defines right and wrong. Combined with this is the wonderful Personality behind it: We find that the keeping these commands—His law—teaches us God's greatest attribute. The law does two things: It shows negative things and positive things. The negative is what sin—wrongdoing—is. The positive is love—the love of God.
His law is a reflection of His character in words. It points the way toward what we are to become. Answer this simple question: Does God call people to salvation and then throw away the road map? It is ridiculous to think such a thing.
The law has a Personality behind it—in terms of love. The law provides the basic outline, and then, when combined with the examples of God's living and acting in both Testaments, it presents a full picture of love. God's actions and Christ's example amplify and make practical what the law says in words.
One has to begin somewhere, and this the law does in providing us with its letter. Then there is its spirit, which is the magnification of the letter, but it does not do away with the law. The law, then, is not only the guideline to what is right and wrong, but the law is also the guideline—in words—to what love is.