Q41: Where is the moral law summarily comprehended?

A: The moral law is summarily comprehended in the ten commandments (Deut. 10:4; Matt. 19:17).


I. The sum total of the moral law is contained in the Ten Commandments (Matt. 19:17).

A. By the Ten Commandments is meant the Decalogue (cf. vv. 18-19).

1. There are only ten commandments (Deut. 10:4).

B. Life promised for fulfilling law (Ga. 3:10, 12).

1. The rich man only considered the letter of the law (Matt. 19:20).

2. No man can perfectly obey the law (Rom. 8:3, 7).


II. The manner the law was delivered.

A. By audible voice from the Lord from Sinai, accompanied with unprecedented terror (“artillery of heaven was fired”) and majesty (Ex. 19:16-20; Heb. 12:18).

1. Terrors of Mt. Sinai teach about God, His law, and our sin.

a. Moses said he was trembling with fear (Deut. 9:19; Heb. 12:21).

Relevant quote from John Calvin:
“We must bear in mind what I have already adverted to, that this terrible spectacle was partly to set the presence of God before their eyes, that His majesty might urge the beholders to obedience, and vindicate His doctrine from contempt, and partly to express the nature of the Law, which in itself produces nothing but mere terror. The air was disturbed by thunder and lightnings, and the sound of the trumpet; the mountain was wrapped in smoke and darkness, that the people might humbly prostrate themselves before God, and solemnly embrace the covenant proposed to them; since religion never penetrates the mind so that it seriously receives God’s word until its vices are cleansed and corrected, and it is really subdued.”

Calvin on Ex. 19:16

2. Natural phenomenon: thunder and earthquakes signs of God’s power; dark cloud denotes mystery—the aspects of His being we cannot penetrate; fire both attracts (warmth) and repels (burns); trumpet, speaks to His sovereignty as it signals king’s arrival.

a. These signs display glory of God, the sum total of His attributes, which He still possesses now.

3. People were commanded to wash, typifying sanctification for reception (Ex. 19:10, 14).

4. Angels were involved in giving of the law (Acts 7:53; Ga. 3:19).

B. The Ten Commandments were written by God’s finger on stone (Ex. 31:18), showing perpetuity.

1. Moses broke tablets (Ex. 32:16, 19) typifying how man would treat the law.


III. The reason the Decalogue was given and renewed.

A. To confirm the moral law after the Fall that it be not lost.

1. Man’s mind had become darkened, his will rebellious, and His affections bent toward darkness (Jn. 3:19).

a. The moral law imprinted on hearts is defective: it could never teach man to mourn over his inherent and sprouting sin (Rom. 7:7); it does not drive men out of themselves for a remedy (Ga. 3:24); nor can it show man the pure and holy condition he was created in (Ecc. 7:29).


IV. The manner in which the law is summed up in the Ten Commandments.

A. The Decalogue: comprises the heads that all other biblical duties can be traced to; was what Christ (Matt. 5-7) and the apostles (e.g., Rom. 13:8-10) chiefly expounded; comprises man’s whole duty (Ecc. 12:13).

B. The Decalogue requires the observance of certain rules to be rightly understood.

1. The law is spiritual, reaching the understanding, will, affections, and all other powers and faculties of the soul, as well as our words, works, and gestures (Ex. 20:17; Matt. 5:21-44; Rom. 7:14).

2. The law requires perfection, and the least defect exposes to the curse (Ga. 3:10).

3. Where a duty is commanded the contrary sin is forbidden (Ex. 20:8-10; Isa. 58:13), and where a sin is forbidden, the contrary duty is commanded (Eph. 4:28).

a. Example: When God forbids murder, He commands us to love our neighbor; when God commands we honor our parents, He forbids we do anything injurious to them.

b. Where a promise is annexed, the contrary threatening is included (Ex. 20:12; cf. Prov. 30:17); where a threatening is annexed, the contrary promise is included (Jer. 18:7-8).

4. Under one sin or duty, all similar are forbidden.

a. Example: Do not murder includes beating, malice, neglecting personal health; command to love neighbor includes doing all good to him within one’s power.

(1). Any sin forbidden includes all means leading thereunto (Rom. 13:14).

5. We are to help others keep the law, and not be accessories to breaking it (Ex. 20:8-10), by encouraging them to sin (Rom. 1:32); setting a bad example (Lk. 17:1-3); failing to prevent it (1 Sam. 3:13); endorsing other’s sin (Acts 7:58; 8:1).

6. Second table of law yields to the first.

a. Example: If the commandment to honor parents comes into competition with Christ we are not bound to it (Lk. 14:26). Parent who tells child to worship a false god is to be disobeyed.


V. Application.

A. Use, of knowledge.

1. The law as man’s rule of obedience is plain to the common sense and reason of man, as it is explained and illustrated in every book in the Bible, and is written in some measure on every heart.

2. The law is perfect, requiring full conformity. Every duty must be perfectly performed, and every least degree of sin is forbidden.

a. Salvation is unattainable as no man can render such obedience.

b. Salvation is suspended solely upon the obedience and satisfaction of Christ.

3. The law is exceedingly broad, reaching to every desire of the heart and every action. It is the rule for heart and life.

B. Use, of testing.

1. Is the moral law our rule for life?

2. Has the moral law become merit before God, in addition to Christ’s work (i.e., “legalism”)?

C. Use, of exhortation: sinners and saints.

1. Sinners. Hebrews 12: The two mountains contrast the law and the gospel (Heb. 12:18-21, 22-24).  Sinai: dark, stormy, fear/danger, designed to keep away. Zion: bright, joy, peace/safety, designed to draw near.

a. Difference is not in God, but on Zion we come on the right side of God’s justice, through “Jesus the mediator…” (v. 24). We must determine where we would meet with God, on Mt. Sinai or Mt. Zion? Jesus alone is the Mediator who brings us close to God. Hebrews 12 thus closes with a warning to not reject the salvation God offers through Christ: “do not refuse Him  that speaks” (vv. 25-26) [because God is coming again in awful majesty to judge].

2. Saints. Consider the breadth of the Law, reaching the heart, and the utter impossibility to keep it; Christ who was “born under the law” (Ga. 4:4), who “fulfill[ed] all righteousness” (Matt. 3:15), and “committed no sin (1 Pet. 2:22), which was no small accomplishment. Therefore, the moral law, by revealing the full extent of our sin, magnifies Christ’s atonement, who was crucified “in order that the righteous requirements of the law might be fully met in us” (Rom. 8:4a). Let us yield obedience sincerely, completely, and cheerfully, as an expression of our love.

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