The rule of obedience: the moral law

This week's questions

What is the duty which God requireth of man? The duty which God requireth of man, is obedience to his revealed will.

Question 39

What did God at first reveal to man for the rule of his obedience? The rule which God at first revealed to man for his obedience, was the moral law.

Question 40

Wherein is the moral law summarily comprehended? The moral law is summarily comprehended in the ten commandments.

Question 41

Last week Question 38 closed the catechism's first part. Here begins the second, the duty God requires, from Question 39 to 107, as Question 3 promised (see the library's introduction). For fourteen weeks, to week 35, we learn the law.

Obedience to his revealed will

First, the word ‘revealed’. Moses drew the line: "The secret things belong to the LORD our God, but the things revealed belong to us and to our children forever, so that we may follow all the words of this law" (Deuteronomy 29:29). We are asked not to search out God's hidden counsel but to do what he has made known, which the first proof text sums up:

He has shown you, O man, what is good. And what does the LORD require of you but to act justly, to love mercy, and to walk humbly with your God?

Micah 6:8

The next is Samuel's rebuke to Saul, who offered sacrifice in place of obedience: "Behold, obedience is better than sacrifice, and attentiveness is better than the fat of rams" (1 Samuel 15:22). Obedience is not the price of God's favour: we are accepted for Christ's righteousness alone (Question 33). It is love's answer to grace. "If you love Me, you will keep My commandments" (John 14:15).

Written on the heart, written on stone

Question 40 says this rule was revealed ‘at first’. The Larger Catechism explains that the rule given to Adam in innocence, "and to all mankind in him", was the moral law, besides the special command about the forbidden tree Larger Catechism, Q. 92. So even those who never received the law of Moses bear its traces, as the first proof text says:

So they show that the work of the law is written on their hearts, their consciences also bearing witness, and their thoughts either accusing or defending them

Romans 2:15

The church has often called this natural law, with conscience as its witness. The next proof text recalls Moses' promise that "The man who does these things will live by them" (Romans 10:5): for Adam this law was the condition of the covenant of life of Question 12 (Providence and the covenant of life).

At Sinai God himself wrote this law on two tablets (Deuteronomy 10:4); Exodus calls them "the words of the covenant — the Ten Commandments" (Exodus 34:28), in Hebrew the ‘ten words’. Jesus too pointed a man asking about life to the commandments (Matthew 19:17). The moral law is ‘summarily comprehended’ in them: the ten are not a list of every duty but the headings under which every duty belongs. So this course reads them by the Larger Catechism's rules Larger Catechism, Q. 99, among them: the law is spiritual, reaching the heart as well as words and deeds; where a duty is commanded the contrary sin is forbidden, and the reverse; and one thing may be required or forbidden in several commandments. Hence each week from now asks what a commandment requires and what it forbids.

The law's three uses, a mirror for our sin, a curb on evil and a rule for the redeemed, are taught in the Reading the Bible course's Law (see WCF 19.6). Writing of the third use, John Calvin, the Reformer of Geneva, says of the joy of Psalm 19 that David "saw the Mediator, without whom it gives no pleasure or delight" Calvin, Institutes 2.7.12. The Lutheran Formula of Concord also teaches a third use for believers Formula of Concord, Art. 6, while Lutherans lay their chief weight on rightly dividing law and gospel. Israel's ceremonial and judicial laws are distinguished from the moral law in WCF 19.3–5.

Counting the commandments, and reading them

Churches number the ten differently. The Reformed, with the Orthodox, the Anglicans and many early Christian writers, count ‘no other gods’ and ‘no graven image’ as two commandments and coveting as one; so the Heidelberg Catechism, after setting out the law Heidelberg Catechism, Q. 92, divides it into two tables of four and six Q. 93. Catholics and Lutherans, following Augustine, join the first two and divide coveting in two. Luther's Small Catechism makes the commandment about God's name the second, and coveting a neighbour's house and coveting his wife and goods the ninth and tenth. So what this course calls the fifth commandment is their fourth. Jewish tradition counts the preface, "I am the LORD your God" (Exodus 20:2), as the first word. The numbers differ; the ten words are the same.

Christians differ, too, on whether the ten bind believers as a rule of life. The Westminster Confession holds that the moral law binds all, "as well justified persons as others", and that Christ in the gospel does not dissolve "but much strengthen, this obligation" WCF 19.5. Dispensational and new covenant readings place Sinai's law within the old covenant with Israel: believers live under the law of Christ, bound by the ten where the New Testament gives them again. See Do Christians have to keep the Old Testament law?, Law and covenant, One covenant of grace in many ages and, on grateful obedience, Guilt, grace and gratitude.

To ponder this week

Do you hear God's commandments this week as a burden, or as the shape of love? "For this is the love of God, that we keep His commandments. And His commandments are not burdensome" (1 John 5:3). However they sound now, read Exodus 20 aloud, a commandment or two a day, and write down what each one protects.

Practice