The Purpose of the Law
By: Dr. Mckay Caston
Tags: Christianity, Gospel, Church, Religion, Grace

Law in the Old Testament

Does it confuse you when preachers and teachers talk about the law of God? I wouldn’t blame you for the angst if you find such terminology to be a kind of Christianese that everyone is supposed to understand but doesn’t. If you count yourself among the perplexed, this post is for you.

A systematic study of the concept of law in the Bible distinguishes between at least three kinds of law. Starting in the Old Testament, we are introduced to the moral law. The focus of the moral law is not about keeping rules. The moral laws are examples of what it looks like in practice to love God with all our heart, mind, and soul and to love other people with selflessness and sacrifice. These examples of love are summarized (although not exhaustively) in what we call the Ten Commandments.

The second type of laws we find in the Old Testament are ceremonial laws. These laws provided clear directions for the priesthood concerning the system of sacrifice that was at the heart of Jewish worship. Ceremonial law also included dietary restrictions and specified how cleansing rituals were to be practiced when someone was designated as “unclean.”

The third category of law in the Old Testament is civil law. As the name implies, these laws functioned as a form of case law that governed the citizens of Israel, which was a formalized, geopolitical nation. Civil law may be the easiest to grasp because we live within the confines of civil law every day as citizens of our own geopolitical state. We have traffic laws, property laws, business laws, personal injury laws, etc. It was the same way with civil law in Old Testament Israel.

What was the community to do if someone was accused and convicted of theft? What was the penalty? What kind of restitution should be paid if you accidentally killed your neighbor’s cow? What about if you intentionally killed it? We could discuss countless examples of practical issues to which the citizens of Israel could appeal for an objective ruling based on civil law.

Law in the New Testament

When we arrive in the New Testament, the ceremonial law is fulfilled in Jesus through his finished, redemptive work of crucifixion where, as the Lamb of God, he is the final sacrifice. We, the unclean, are made clean through the shed blood of the Lamb.

Likewise, by the New Testament, the civil law has expired. That is the terminology used in The Westminster Confession of Faith (Chapter 19, Section 4), which says, “To them also (the nation of Israel), as a body politic (a nation), he gave [various] judicial laws, which expired… with the state of that people, not obliging any other now, further than the general equity thereof may require.”

Therefore, with the ceremonial and civil law no longer binding for the church, which Paul calls the New Israel, we are left with the moral law. Sometimes, law is used to refer to the first five books of the Bible, called the Torah. But for our purposes, when we read law in the New Testament, the meaning is not ceremonial, or judicial, but moral.

When we speak of moral law, it is implied that there is a standard of morality that defines what is true, good, and beautiful in contrast to that which is a lie, is evil, and is abhorrent to God. The Lord is not only the creator of the material universe. He is the designer of the moral universe in which every human lives.

In the same way that we have objective civil laws that govern the flow of traffic, there are objective moral laws that govern the flow of human relationships. I may not agree with the traffic laws and may transgress them, thinking I know better than those who designed the road system. But traffic laws are intended to provide boundaries and limits so that we can safely enjoy the roads.

The same is true with the moral law. It is intended for our good, creating boundaries and limits that are established for human flourishing. What if there were no traffic laws. Driving would be chaos. The same is true in the moral universe.

Yet, just like we often determine what is right in our own eyes and drive faster than the law allows, we live our moral lives according to what is right in our own eyes. This is instructive because, just like we resist and defy speed limits, at the heart of human sin is a defiant resistance to submit and conform to the moral law of God.

The question is, what will I do when I finally get busted? Will I make excuses? Will I plan to defend myself in court? Or will I confess my guilt and plead for mercy?

These questions find their answer in Galatians 3:15–25 as the apostle Paul explains the purpose of the moral law.

15 Brothers and sisters, let me take an example from everyday life. Just as no one can set aside or add to a human covenant that has been duly established, so it is in this case. 16 The promises were spoken to Abraham and to his seed. Scripture does not say “and to seeds,” meaning many people, but “and to your seed,”] meaning one person, who is Christ. 17 What I mean is this: The law, introduced 430 years later, does not set aside the covenant previously established by God and thus do away with the promise. 18 For if the inheritance depends on the law, then it no longer depends on the promise; but God in his grace gave it to Abraham through a promise. 19 Why, then, was the law given at all? It was added because of transgressions until the Seed to whom the promise referred had come. The law was given through angels and entrusted to a mediator. 20 A mediator, however, implies more than one party; but God is one. 21 Is the law, therefore, opposed to the promises of God? Absolutely not! For if a law had been given that could impart life, then righteousness would certainly have come by the law. 22 But Scripture has locked up everything under the control of sin, so that what was promised, being given through faith in Jesus Christ, might be given to those who believe. 23 Before the coming of this faith, we were held in custody under the law, locked up until the faith that was to come would be revealed. 24 So the law was our guardian until Christ came that we might be justified through faith. 25 Now that this faith has come, we are no longer under a guardian.

The Covenant of Law and the Covenant of Grace

In the verses which immediately precede this text, Paul has been arguing that Christians are not reconciled to God as forgiven sons and daughters because of the promises we make to God but because of the promise God makes to us. It is a promise that the Lord first made in Genesis 3:15 and that is repeated throughout biblical history. This promise is called a covenant, which is a binding agreement between two people.

For example, marriage is a covenant. It is a legally binding agreement. The essence of the agreement is a promise, which the man and woman speak out loud in front of witnesses as vows.

Two primary covenants run through the Bible. One is the covenant of law (or works), which demands perfect obedience. The other is the covenant of grace, which provides for our disobedience with someone else’s obedience.

Alluding to Abraham in verses 15–18, Paul demonstrates how the covenant of grace is a promise that we are called to believe. We don’t earn the promise. We don’t deserve the promise. We just receive it.

In verse 19, Paul asks why the law was given. The answer: because of transgressions. Remember our tendency to break speeding laws? In Romans 3:20, he puts a razor’s edge on this idea, saying, “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.” The blue lights in the mirror tell us we have transgressed the law. There is nothing we can do but pay the fine. Or have someone else pay it for us.

Law as Love

Here we have the ultimate purpose of the moral law, which is not to show us how to be good enough to be accepted by God as good, decent people. The moral law is not to be used as a weapon with which to condemn other sinners and make ourselves feel superior. The moral law was given to show us how naturally selfish and unloving we are in the flesh and how desperate we are for the mercy of God. We need to highlight the word unloving because that is what it means to “break the law of God.” As we said, every moral law is an example and application of what it looks like to love either God or our neighbor.

So what does it mean to love? Where do we get our definition? The apostle John tells us in 1 John 4:9–11,

“9 This is how God showed his love among us: He sent his one and only Son into the world that we might live through him. 10 This is love: not that we loved God, but that he loved us and sent his Son as an atoning sacrifice for our sins. 11 Dear friends, since God so loved us, we also ought to love one another.”

The perfect description of love is the ross of Jesus, where we learn that to love is to die for the sake of someone else. Not always literally. Nevertheless, to love means that I am willing to suffer and sacrifice for the good of someone who does not deserve my suffering and sacrifice.

That is love.

This is where the analogy of breaking a speed limit and breaking the moral law breaks down. I don’t have a relationship with the traffic commission. But I do have a relationship with God, whether I know it or not. In fact, every human has a personal relationship with God. The issue is whether it is a reconciled relationship or an estranged one.

The law shows us that our sin is not about breaking rules like speed limits. It is a failure to love God. The willful, defiant way in which we resist his wisdom and ways as revealed in the moral law exposes a heart that hates authority — especially the authority of God.

Like a mirror, the law allows us to see who we really are.

If God is a King, and he is, then sin is treason. And we know what the penalty is for treason. Now we also know in a fuller way the meaning of Galatians 3:13, where Paul proclaims good news for traitors, saying, “Christ redeemed us from the curse of the law by becoming a curse for us!” On a cross, King Jesus became a traitor in our place, suffering the penalty we deserved for our crimes against the very King who gave his life for the guilty.

Law and Gospel, Not Law Against Gospel

This is why Paul says in verse 21 that the law is not opposed to the gospel but functions hand in hand with the gospel. Faithful preachers will not preach law or gospel but law and gospel. Why? Paul tells us in verse 24, “The law was our guardian until Christ came that we might be justified by faith.

The word Paul uses for guardian in the 2011 version of the NIV is translated with various words in English, including schoolmaster and tutor, giving the impression that the law is essentially a teacher. I like to think of the law as a professor of grace disguised as a disciplinarian who knows that if repetition is the mother of learning, failure is the father.

From this perspective, helping me come to grips with my rebellious heart that resists the authority and the wisdom of God by revealing my selfish and unloving sin nature is not the work of a cruel master but of a loving friend who longs for us to see the wonder, beauty, and transforming power of God’s grace in the cross. The law is not my enemy. It is a friend who is willing to wound in order to heal.

Justified through Faith

The three words of verse 24 must not be overlooked or underemphasized. “Justified through faith.” This is the doctrine that separates the Christian message from every other religion the world has known.

Religion says, “Do this and live.”

Christianity says, “Believe this and live.”

Remember, to be justified is to be declared perfectly righteous before the law, as if we had obeyed every command to love every moment of our lives and had never sinned. Not once. It is to be seen as morally pure and as holy as Jesus himself.

It is this holiness that is required for heaven. But no one can achieve holiness by human effort. Thankfully, it is this holiness that God provides and gives to any who confess their need and will receive the gift of righteousness Jesus earned by fulfilling the law with perfect obedience, culminating with the perfect love demonstrated in the cross.

When Paul writes in verse 25, “Now that this faith has come, we are no longer under a guardian,” he signals that the believer has an entirely new relationship to the law. No longer “under” means we have graduated from the tutorship of the law. Just like university professors celebrate the graduation of their pupils, so the law celebrates when we graduate from attempts to justify ourselves and finally find our justification in Christ alone.

Paid in Full

John Beukema tells a personal story about his attempt to get a new driver’s license after moving from Massachusetts to Pennsylvania. A typically simple process revealed an unexpected problem. To John’s surprise, the DMV desk clerk informed him that his license had been suspended. In reply to being informed of the suspension, he retorted, “There must be a mistake. I’ve never done anything to deserve that.”

Five phone calls later, he discovered that ten years prior, he had failed to pay a certain tax that had been accruing penalties of hundreds of dollars. Before John would be able to secure his new license, the bill had to be settled. It was a frustrating bill he wasn’t expecting to pay. Thankfully, it wasn’t a devastating penalty.

Like yours and mine.

Whether we use the image of a tutor or desk clerk at the DMV, the moral law is designed to reveal the problem we all face and the penalty we all deserve. It is a penalty that has been accruing for years and demands far more than a few hundred bucks. Some may respond like John, “I’ve never done anything to deserve that.” But if we are brutally honest, it doesn’t take much to confess that we do deserve it.

Even though Jesus didn’t deserve it, he suffered the penalty for us, paying in full the demands of justice so that we can receive the gift of complete, imputed, perfect righteousness. Completely forgiven. Completely accepted. Completely loved.

Here is what this means concerning the purpose of the law.