The Purposes of the Law

By William J. McRae [1]

An exposition of Exodus 20

Introduction

This passage presents one of the most awesome and terrifying moments of all history. Three days earlier Israel had arrived at the foot of Mt. Horeb, the mount of God, in the range at Sinai. For two days the most careful preparations had been under way. It was now the third day.

A heavy thick black cloud broke upon them, enveloped the mountain, and settled over the camp. Then followed great roars of thunder that shattered the silence and bright flashes of lightning that pierced the darkness. Moses directed the terrified people to the foot of the mountain where they stood in holy reverence. A blazing fire descended from the distant heavens to the top of the mountain. Smoke began to billow heavenward as from a towering inferno. The entire mountain began to tremble like a mound of Jello.

What is the meaning of such a dramatic visual presentation? Surely it is to impress upon the children of Israel the majestic power of their sovereign God. But more than that, it highlights the tremendous importance of this solemn occasion. And what is the occasion? It is the giving of the Law. After Yahweh had spoken we read:

All the people perceived the thunder and the lightning flashes and the sound of the trumpet and the mountain smoking; and when the people saw it, they trembled and stood at a distance. Then they said to Moses, “Speak to us yourself and we will listen; but let not God speak to us, or we will die.” Moses said to the people, “Do not be afraid; for God has come in order to test you, and in order that the fear of Him may remain with you, so that you may not sin” (Ex. 20:18–20).

This visual display was to inject into them such a fear of God that they would not sin and such a reverence for Him that they would wholly obey His Law.

In this article we want to consider the purposes of this Law. Why did God give these Ten Commandments?

Some time ago two young men came to the front door of our home to share their faith. My wife answered the door and a short way into their presentation interrupted them with a question. She admitted to them she was a sinner and confessed she was concerned about meeting God, having salvation, and going to heaven. Her question was, “How can a guilty sinner like me get to heaven? What must I do?” The spokesman for the two traveling “evangelists” assured her that if she kept these ten commandments, all would be well with her God.

What a devastatingly discouraging answer. Who among us has done this? Who has kept them? “Well, “ you say, “Of course no one has perfectly kept them. What God requires is that we do the best we can. If we try our best, all will be well.” To such a person I would ask, “Where did God ever say that?” Or I might even ask, “Who among us has done this? Who has done the best he could?”

In spite of such obvious futility, there are thousands today who see this to be the purpose of the Law, the essence of Christianity, and the way of salvation.

Such persons remind me of the philosopher who once said to a preacher that his philosophy of religion and Christianity was the golden rule. The preacher, trying to point out how inadequate a concept of Christianity that was, asked the philosopher, “Would you like to hear my philosophy of astronomy? It is, ‘Twinkle, twinkle little star, How I wonder what you are. Up above the world so high, Like a diamond in the sky. Twinkle, twinkle little star, How I wonder what you are.’“

The man who proposes such a purpose for the Law has just condemned himself by his failure to keep it. He has plunged himself into a hopeless despair. If there is a word of hope for such a person it is this: The Law was not given as a way of salvation.

Nevertheless knowing that a man is not justified by the works of the Law but through faith in Christ Jesus, even we have believed in Christ Jesus, so that we may be justified by faith in Christ and not by the works of the Law; since by the works of the Law no flesh will be justified (Gal. 2:16).

Is the Law then contrary to the promises of God? May it never be! For if a law had been given which was able to impart life, then righteousness would indeed have been based on law (Gal. 3:21).

What then is the purpose of the Law? A careful reading of both the Old and New Testaments will reveal the fact that the Law has at least a four-fold purpose in the plan of God.

The Decalogue Is the Rule of Life for God’s Covenant People

So He declared to you His covenant which He commanded you to perform, that is, the Ten Commandments; and He wrote them on two tablets of stone (Deut. 4:13).

The decalogue, then, is the text of the so-called Mosaic covenant. In the account of Exodus 20 the form of the ancient treaties can be easily discerned.

• The Preamble: “I am the Lord your God” (20:2). This establishes Yahweh’s right to impose a covenant upon them.
• The Historical Prologue: “Who brought you out of the land of Egypt, out of the house of slavery” (20:2). This establishes Israel’s obligation to Yahweh. He has acted in grace toward them.
• The Stipulations: The ten words. This is a summary of the stipulations of the covenant Yahweh is imposing upon Israel. Here is Israel’s obligation to the Lord. It is His rule for their life.
• The Blessings and Curses: These are interspersed throughout the stipulations. See verses 5, 6, 7, 12.

It is important to note that it was not by means of keeping these stipulations that Israel became the people of God. They were His people and were His by sovereign election. By virtue of His gracious and sovereign election they were the people of God. They never sought to attain that status by keeping the Law. They were given that status by grace.

It should also be noted that the decalogue summarizes the obligations of God’s elect and redeemed people to Him for His grace toward them. It was their rule of life. It finds its counterpart in Romans 12–16 (our obligations to the Lord in response to His grace recorded in Romans 1–11); or in Ephesians 4–6 (our obligations in response to His grace recorded in Ephesians 1–3).

The Mosaic covenant was a conditional covenant — the blessings were conditioned on obedience. When Israel obeyed the Law, God blessed them in a thousand ways. When they disobeyed, they fell under the chastening hand of their God. Israel’s covenant relationship with God was never in jeopardy. They were His by election and redemption, both of which were founded upon grace! But their enjoyment of the blessings of the covenant was conditioned upon their obedience to these stipulations.

Of course, the history of Israel is a history of failure. They proved unfaithful to their commitment to do all that the Lord commanded. They violated the treaty terms over and over again. They stumbled over the stipulations and fell before the Lord. It was in anticipation of this inevitable plight that the sacrificial system were instituted at Sinai. Here was a way to atone for their sin, for the broken Law. The shed blood of a spotless lamb was a sufficient offering to appease the wrath of God and satisfy the just demands of a broken Law. How significant it is that at Sinai, where the Law was given, the Tabernacle and its sacrificial system was instituted.

But subsequent revelation in Scripture reveals there is much more here in the purpose of God giving the Law than this.

The Decalogue is a Revelation of the Holiness of God

But like the Holy One who called you, be holy yourselves also in all your behavior (1 Pet. 1:15).

This is perhaps the primary purpose of the Law. It is to reveal to Israel and all the world the character of God. The fact of His holiness is made abundantly clear in this Law (Heb. 12:18, 29; Deut. 28:58). All the requirements laid upon the nation are in the light of His holy character.

The holiness of God is a concept virtually effaced from modern society. That is the character of our God. “He is absolutely holy with an infinite, incomprehensible fullness of purity that is incapable of being other than it is.” [2]

The Decalogue is a Mirror Exposing the Sinfulness of Man

This is the word of the apostle when he says that the Law “was added because of transgressions” (Gal. 3:19). The Abrahamic covenant had lacked any emphasis on sin. The Mosaic covenant was added because of the abounding of sin in order to reveal to man his sinfulness. Paul continues: “But the Scripture has shut up all men under sin” (Gal. 3:22).

J. Dwight Pentecost has somewhere stated the point simply, “The holiness of God as revealed in the Law became the test of man’s thoughts, words, and actions, and anything that failed to conform to the revealed holiness of God was sin.”

In his Institutes Calvin wrote, “The Law is like a mirror. In it we contemplate our weakness, then the iniquity arising from this, and finally the curse coming from both — just as a mirror shows us the spots on our face.” [3] It brings to light and causes us to face up to the fact of our sinfulness, our weakness, and our bondage.

This is precisely how Paul uses the Scriptures of the Old Testament in Romans 3. He lifts them up as mirrors before the faces of all men, and in the light of its pages proves that all men, whether Jew or Gentile, are under sin.

Now we know that whatever the Law says, it speaks to those who are under the Law, so that every mouth may be closed and all the world may become accountable to God; because by the works of the Law no flesh will be justified in His sight; for through the Law comes the knowledge of sin (Rom. 3:19–20).

This is precisely how the Law still works today. Take a careful look at these ten words.

The First Commandment

You shall have no other gods before Me (Ex. 20:3).

“Beside me” probably means “in preference to me” or “in precedence over me.” This forbids a deliberate choice of placing oneself in vassalage to another god (Deut. 6:5; 8:11, 17, 19). This demands absolute allegiance to Yahweh and becomes the basic stipulation. To put boyfriend or girlfriend, husband or wife, employer or the president before God is to sin.

The Second Commandment

You shall not make for yourself an idol, or any likeness of what is in heaven above or on the earth beneath or in the water under the earth. You shall not worship them or serve them; for I, the Lord your God, am a jealous God, visiting the iniquity of the fathers on the children, on the third and the fourth generations of those who hate Me, but showing lovingkindness to thousands, to those who love Me and keep My commandments (Ex. 20:4–6).

This continues the theme of the first commandment by requiring once again the full allegiance of Israel. However, it becomes more specific by forbidding idolatry. No object is to be made in order that one bow to it. God is a very jealous God! To bow down in worship before any object is to sin.

The Third Commandment

You shall not take the name of the LORD your God in vain, for the LORD will not leave him unpunished who takes His name in vain (Ex. 20:7).

Here we are forbidden to utter the name of Yahweh hypocritically — for selfish purposes (Psalm 41:7), to support false pretensions regarding prophecy (Jer. 27:15), or in committing perjury in a court of law (Lev. 19:12). To so abuse the name of the Lord is to sin.

The Fourth Commandment

Remember the sabbath day, to keep it holy. Six days you shall labor and do all your work, but the seventh day is a sabbath of the Lord your God; in it you shall not do any work, you or your son or your daughter, your male or your female servant or your cattle or your sojourner who stays with you. For in six days the Lord made the heavens and the earth, the sea and all that is in them, and rested on the seventh day; therefore the Lord blessed the sabbath day and made it holy (Ex. 20:8–11).

The sabbath day is to be set apart from work for holy purposes. For an Israelite to violate this was sin. It is interesting that this is the only one of the ten commandments which is not repeated and imposed upon believers under the new dispensation.

The Fifth Commandment

Honor your father and your mother, that your days may be prolonged in the land which the LORD your God gives you (Ex. 20:12).

Here we are commanded to honor our mother and father, that is, to esteem them as persons of great value and worth and to regard them as such. This is the first and only commandment with a promise! Failure is sin.

The Sixth Commandment

You shall not murder (Ex. 20:13).

Premeditated killing (Ex. 21:14) and manslaughter (Deut. 4:42), any illegal killing, is forbidden in this word. Such killing is sin.

The Seventh Commandment

You shall not commit adultery (Ex. 20:14).

The inviolability of marriage is hereby established for the community life of Israel. The adulterer not only violates the law of God, but also attacks the rights of God before whom his marriage was concluded. To do so is to sin.

The Eighth Commandment

You shall not steal (Ex. 20:15).

Prohibited here is “not only the secret or open removal of another person’s property, but injury done to it, or fraudulent retention of it through carelessness or indifference (Ex. 21:33; 22:13; 23:4; Deut. 22:1–4).”4 To steal is to sin.

The Ninth Commandment

You shall not bear false witness against your neighbor (Ex. 20:16).

In this precept Yahweh commands them not to “answer as a false witness against your neighbor.” They are forbidden to be a false witness for any vain or selfish purpose. To play the role of a false witness is to sin.

The Tenth Commandment

You shall not covet your neighbor’s house; you shall not covet your neighbor’s wife or his male servant or his female servant or his ox or his donkey or anything that belongs to your neighbor (Ex. 20:17).

The personal rights of every individual are protected by this word. To violate his rights is to sin.

How sharp and clear is the image seen in this mirror. It expresses the sinfulness of every heart. But helpful as a mirror is in revealing filth, it is useless for removing it. Helpful as the Law is in exposing sin, it is useless in removing it. Where shall we turn for cleansing and forgiveness?

The Decalogue Is a Tutor to Lead Us to Christ

Therefore the Law has become our tutor to lead us to Christ, that we may be justified by faith (Gal. 3:24).

Admittedly Paul has in mind the entire Law of Moses when he says it is our tutor, yet the decalogue which is the summary text of the Law is surely it as well. It is our tutor to lead us to Christ.

The translation of the authorized text, “schoolmaster,” is not a satisfactory one.

It cannot be denied that in the execution of his duties the ancient “pedagogue” might also impart some elementary and useful instruction on various matters, but that was not his primary function. In the figure here used the “pedagogue” is the man — generally a slave — in whose custody the slaveowner’s boys were placed, in order that this trusted servant might conduct them to and from school, and might, in fact, watch over their conduct throughout the day. He was, accordingly, an escort or attendant, and also at the same time a disciplinarian. The discipline which he exercised was often of a severe character, so that those placed under his guardianship would yearn for the day of freedom. And, as has been shown…that was exactly the function which the law had performed. It had been of a preparatory and disciplinary nature, readying the hearts of those under its tutelage for the eager acceptance of the gospel of justification…by faith in Christ. [5]

The person who has looked into the mirror of the Law, and seen himself in his sin and need before God, is ready for the gospel of Jesus Christ.

Conclusion

George Whitefield, the great preacher, was born in the county of Gloucester, England, on the sixteenth of December, 1714. During his early years he was the subject of serious impressions, but according to his own account they were not sufficient to restrain the evil propensities of his nature. At the age of sixteen he says: “I began to fast twice in the week for nearly thirty-six hours together, prayed many times a day, received the sacrament every Lord’s Day, fasting myself almost to death all the forty days of Lent, during which I did not go less than three times a day to public worship, besides seven times to private prayers, yet I knew no more that I needed to be born again, born a new creature in Christ Jesus, than if I never was born at all. Then by God’s grace Charles Wesley put a book in my hand whereby God showed me that I must be ‘born again’ or damned.”

This is a most extraordinary testimony, showing how far a man may go and not be saved. The words of the Lord Jesus are plain, “Except a man be born again, he cannot see the Kingdom of God” (John 3:3).

After his conversion to God Whitefield became an eloquent and powerful preacher of the Gospel. He is said to have preached over a thousand times from the text, “Ye must be born again,” and to all kinds of audiences, from the very roughest to that of the highest and noblest in the land. The effect of his preaching was so remarkable that great audiences are described as being “drenched in tears.” “How can I help weeping,” he said to them, “when you have not wept for yourselves,” and they began to weep.

You must be born again. Turn from yourself. Trust God’s own dear Son to save. Receive Him into your life this very moment as the One who has died for your sin, as the One who has borne your guilt, as the One who has satisfied all God’s just demands against you.

Notes

1. Emmaus alumnus Bill McRae, well-known Bible expositor, author, and educator, presently serves at Tyndale College and Seminary (Ontario) as President Emeritus and Minister at Large. This is the fifteenth and last in a series of expositions on the book of Exodus.
2. A. W. Tozer, The Knowledge of the Holy (New York: Harper & Brothers, 1961), 112–113.
3. John Calvin, Institutes of the Christian Religion, ed. John T. McNeill, trans. Ford Lewis Battles, LCC, 2 vols. (Philadelphia: Westminster, 1960), II. vii. 7 (vol. 1, p. 355).
4. C. F. Keil and F. Delitzsch, Biblical Commentary on the Old Testament: The Pentateuch, trans. James Martin, reprint ed., 3 vols. (Grand Rapids: Eerdmans, [= 1864]), 2:124.
5. William Hendriksen,, Exposition of Galatians, New Testament Commentary (Grand Rapids: Baker, 1968), 148.