What is the purpose of the Mosaic Law?

To expose sin, then, to detect it in its innermost working, to manifest its utter sinfulness, provoked and aroused by the very presence of good, — this was the aim and object of the law.

The truth is, as the apostle teaches us, "the law entered that the offence might abound." (Rom. 5:20) This shows us, very distinctly, the real object of the law. It came in by the way in order to set forth the exceeding sinfulness of sin. (1 Cor. 7:13) It was, in a certain sense, like a perfect mirror let down from heaven to reveal to man his moral derangement. If I present myself, with deranged hair, before a mirror, it shows me the derangement, but does not set it right. If I measure a crooked wall, with a perfect plumb-line, it reveals the crookedness, but does not remove it. If I take out a lamp on a dark night, it reveals to me all the hindrances and disagreeables in the way, but it does not remove them. Moreover, the mirror, the plumb-line, and the lamp, do not create the evils which they severally point out; they neither create nor remove, but simply reveal. Thus is it with the law; it does not create the evil in man's heart, neither does it remove it; but, with unerring accuracy, it reveals it.

We may wish then to ask why did God propose the law, if He knew from the outset what the result would be? This is virtually the question that Paul raises in Galatians 3:19. He answers it by saying, "It was added because of transgressions," while they were waiting for the advent of Christ, the promised Seed. The force of this becomes clearer if we read Romans 5:13; and Romans 7:7-13. God gave the law to Israel that by it they might have their sinful state brought home to them. Sin is lawlessness, and it was filling the earth from the days of the fall; but, immediately the law was given, a clear line was drawn, and stepping over that line a man became a definite transgressor. His sin could now be imputed to him in a way not possible before. God intended that in Israel definite proof should be given of the fallen and sinful state in which men were found.

This is exactly the question with which verse 19 opens. The answer to this is very brief, and it appears to be twofold. In the first place, it was given in order that men's sins might become, in the breaking of it, definite transgressions. This point is more fully stated in Romans 5:13. In the second place, it served a useful purpose in connection with Israel, filling up the time until the advent of Christ, by proving their need of Him. It was ordained through angels, and through a human mediator, in the person of Moses. But then the very fact of a mediator supposes two parties. God is one; who is the other? Man is the other. And since the whole arrangement was made to hinge upon the doings of man, the other party, it promptly failed.

In definitely convicting men of transgressions the law has done a work of extreme importance. What is right, and what is wrong? What does God require of men? Before the law was given there was some knowledge, and conscience was at work, as is indicated in Romans 2:14-15. But when the law came, all vagueness disappeared; for all, who were under it, the plea of ignorance totally disappeared and, when brought into judgment for their transgressions, not a shred of an excuse remained. We Gentiles were never formally placed under it, but as a matter of fact we know about it, and our very knowledge of it will make us amenable to the judgment of God in a way and degree unknown to the savage and unenlightened tribes of the earth. So let us take care.

The law worked in two ways. In the first place the sins which man committed became exceedingly sinful, because they not only practised what was evil, but they did so after God had plainly forbidden it. In the second place, sin in the flesh, lust, the condition of man after the flesh was detected. The flesh loved sin; and even a converted man who sought to conquer it, was overcome and made captive by the power of sin which ruled in the flesh. By the law is the knowledge of sin, that is, sin in the flesh, and through the law, sins became exceeding sinful. If my child is accustomed to be idle and run about the streets, it is a bad habit, but if I forbid him to go out, and he does it again, it is a positive transgression and much worse than a bad habit. It was for this, to instruct us, to teach us what we are, that the law was given. The law is holy, just, and good; it presents to man his duty as a child of Adam before God, but it was given to man when he was already a sinner not surely to produce sin, but to change sin into offences. The apostle speaks still more positively to the Romans: "The law entered that the offence might abound," v. 20. Moreover, it disclosed to man his evil nature: but I will not here say more. It is enough if the nature and working of the law are understood.

"Wherefore then serves the law; It was added because of transgressions, till the Seed should come," etc. Here we have God's answer to the query. All hope of salvation for men rested from the first on the long-promised Seed — the Son of God. For His advent the pious yearned and prayed for ages. God filled the waiting time with instruction of the deepest possible importance, using various means for this purpose. Thus the law was given in order to make manifest the awful evil of sin, God intending in this way to prepare men for the coming of the Sin Bearer. Tested by the holy enactments of Sinai, men found themselves transgressors. Such is man's nature that the application of God's law to it only provokes its evil. Hence the startling statement "the strength of sin is the law" (1 Cor. 15:56). As a natural consequence, therefore, "the law works wrath" (Rom. 4:15); it can do naught but curse all who are under its claim (Gal. 3:10). In keeping with this the law is described in 2 Cor. 3 as the ministration of condemnation and of death. As a plummet it shows man his crookedness; as a mirror it shows him his vileness; but help him it cannot. "It is weak through the flesh" (Rom. 8:3).

"What purpose then does the Law serve? It was added because of transgressions, till the Seed should come to whom the promise was made" (v.19). Law was not added as a condition placed on the former covenant (for that would be legally and morally wrong), but as a step toward the fulfillment of promise, a step which both disposed of every attempted claim of mankind and established the truth that any blessing to come was entirely dependent on God Himself. Thus the coming of the Seed -- the fulfillment of promise -- was the conclusive proof that the Law was merely a parenthesis, having nothing to do with the promise.

The law "came in" as it were (though of course it was perfect in itself) "by the bye," between the promises and the accomplishment of the promises, to shew what the condition of man would be if he stood on his own ground before God. The law was not before the promises, the apostle argues (Gal. 3), "that it should make the promise of none effect." Promise was given first. And "He to whom the promises were made" came after the law. Meanwhile the law entered in order to manifest what man was, and the effect that would be produced on man when placed on the ground of obedience to the known will of God.*

A passage I have not yet quoted requires to be noticed. "The law was added, because of transgressions." This is constantly cited as if it meant to restrain them. But it really means, I have not the least doubt, to introduce them — thus convincing man of his perverse and wicked will. The law could not be added to restrain them, because there were none until it came; for where no law is, there is no transgression. It was added to turn evil in man's heart into transgression by positive commandment, and give the knowledge of sin to the easy conscience of man. It is important to distinguish between the law as a dispensed government of a single people, and law, the effect of law, on the human heart. The English Authorized Version will help us little as to this, though the great body of the Apostle's argument is founded on the nature and effect of law on the human heart.

In chapter 3:20 the point is, that the fulfilment of an absolute promise depends only on the faithfulness of one; but that the law having a mediator, Moses, two parties were implied, but God is only one. Hence, blessing under the law depends on the faithfulness of another as well as of God, and hence all fails. The promise was confirmed before God to Christ. Christ came after the failure, and we rest on the work of the Mediator, and not on the work of the second party. The law was added to produce transgression, not sin.