1. God gave to Adam a law, as a covenant of works, by which He bound him and all his posterity, to personal, entire, exact, and perpetual obedience, promised life upon the fulfilling, and threatened death upon the breach of it, and endued him with power and ability to keep it (Gen. 1:26–27; 2:17; Rom. 2:14–15; 10:5; 5:12, 19; Gal. 3:10, 12; Eccl. 7:29; Job 28:28).
This covenant in our circles is called the "covenant of creation." The "covenant of works" used here is fine if the terms are defined, but the phrase itself is an unhappy one. It leads people to think it carries its own definition on its face, and hence folks think of some sort of salvation by works. This leads people to assume two different ways of salvation—grace and works. But the Westminster theologians here are clearly thinking of a gracious covenant—God "endued him with power and ability to keep it."
But there was clearly a covenant in the Garden. A covenant is a solemn bond, sovereignly administered, with attendant blessings and curses. The charge to Adam was certainly solemn, God administered it by speaking the words of it, and he promised death for disobedience and continued obedience would bring with it maintained access to the tree of life. This covenant was with Adam and all his posterity. It obligated us to entire obedience, and obligates us still. The fact that it is broken does not mean it ceases to be binding. If a man and a woman commits adultery once, this does not give them permission to continue. The fact that Adam was unfaithful does not mean we have a right to be unfaithful. Another way of expressing this is that outside of Christ we are constantly breaking covenant with God. Our rebellion is ongoing.
2. This law, after his fall, continued to be a perfect rule of righteousness; and, as such, was delivered by God upon Mount Sinai, in ten commandments, and written in two tables (James 1:25; 2:8, 10–12; Rom. 13:8–9; Deut. 5:32; 10:4; Exod 24:1): the first four commandments containing our duty towards God; and the other six, our duty to man (Matt. 22:37–40).
The standards of morality did not change as a result of the Fall. Just as the ten commandments are summarized by the two great commandments—love God and love your neighbor—so they are summarized by the one great commandment before the Fall, which was to not eat of the fruit of the tree of knowledge.
The first table of the law, the first four commandments, describe our obligations to God, and the last six describe our obligations to man. This same division is seen in the two great commandments as well, where we are told to love God and to love our neighbor..
3. Besides this law, commonly called moral, God was pleased to give to the people of Israel, as a church under age, ceremonial laws, containing several typical ordinances, partly of worship, prefiguring Christ, His graces, actions, sufferings, and benefits (Heb. 9; 10:1; Gal. 4:1–3; Col. 2:17); and partly, holding forth divers instructions of moral duties (1 Cor. 5:7; 2 Cor. 6:17; Jude 23). All which ceremonial laws are now abrogated, under the new testament (Col. 2:14, 16–17; Dan. 9:27; Eph. 2:15–16).
The common name for this is the moral law, but by this we do not mean that other commandments of God are not moral. In addition to this "moral" law, God gave other requirements to Israel as the immature Church. The ceremonies given to Israel were given as a prefigurement of Christ's person and work, and as such remain a source of instruction for Christians today. Under the new testament, they do not remain binding on Christians today as ceremonies. They do remain as instruction. Various moral instructions are mixed in with them, and these moral instructions remain binding.
4. To them also, as a body politic, He gave sundry judicial laws, which expired together with the State of that people; not obliging any other now, further than the general equity thereof may require (Exod. 21; 22:1–29; Gen. 49:10; 1 Pet. 2:13–14; Matt. 5:17, 38–39; 1 Cor. 9:8–10).
God gave Israel particular judicial laws. A particular command at a particular time does not necessarily extend to others. The fact that God commanded Israel to invade Canaan does not require us to invade Canaan. At the same time, the fact that God was the one speaking these commands should make us take note. We are required to reason by analogy, and extend the general equity of the law to our situations. For example, God required a parapet around the roofs of houses, and a man was guilty of culpable negligence if someone fell off his roof when a parapet was not there. We do not spend time on our roofs, as they did, and so the requirement as such does not apply to us. But the general equity does bind us, and we are required to put a deck rail around a second story deck.
This should remind us of the vast difference between "top down" approaches to civil law (Justinian), and "historical, linear" approaches to civil law, i.e. common law. In many cases, people are afraid of theonomy because they assume it to be the former and not the latter. But the theonomic system is a case law system, a common law system. King Alfred established common law among us by applying the law of Deuteronomy to his people—but he did not just apply the standards, he also applied the method.
5. The moral law doth for ever bind all, as well justified persons as others, to the obedience thereof (Rom. 13:8–10; Eph. 6:2; 1 John 2:3–4, 7–8); and that, not only in regard of the matter contained in it, but also in respect of the authority of God the Creator, who gave it (James 2:10–11). Neither doth Christ, in the Gospel, any way dissolve, but much strengthen this obligation (Matt. 5:17–19; James 2:8; Rom. 3:31).
The moral law, and the moral aspects of all other laws, is perpetually binding on all men, Christian and non-Christian alike. We are bound by the moral law proper: we must love the Lord our God with all our hearts, souls, minds, and strength. We are bound by the moral law when it is mixed in with ceremonial requirements: we must keep the festival of Passover by ridding ourselves of the yeast of malice and wickedness. We are bound by those aspects of the moral law visible in the particular judicial requirements given to Israel: we must not allow women in combat because it is not right to boil a kid in the mother goat's milk.
We are not under law but under grace (Rom. 6:14). This means that sin shall not be our master. Being under grace does not mean that we now "get" to sin; it means we have been liberated from it, with the definition of sin remaining what it has been through all ages—lawlessness.
6. Although true believers be not under the law, as a covenant of works, to be thereby justified, or condemned (Rom. 6:14; Gal. 2:16; 3:13; 4:4–5; Acts 13:39; Rom. 8:1); yet is it of great use to them, as well as to others; in that, as a rule of life informing them of the will of God, and their duty, it directs and binds them to walk accordingly (Rom. 7:12, 22, 25; Ps. 119:4–6; 1 Cor. 7:19; Gal. 5:14, 16, 18–23); discovering also the sinful pollutions of their nature, hearts, and lives (Rom. 7:7; 3:20); so as, examining themselves thereby, they may come to further conviction of, humiliation for, and hatred against sin (James 1:23–25; Rom. 7:9, 14, 24), together with a clearer sight of the need they have of Christ, and the perfection of His obedience (Gal. 3:24; Rom. 7:24–25; 8:3–4). It is likewise of use to the regenerate, to restrain their corruptions, in that it forbids sin (James 2:11; Ps. 119:101, 104, 128): and the threatenings of it serve to show what even their sins deserve; and what afflictions, in this life, they may expect for them, although freed from the curse thereof threatened in the law (Ezra 9:13–14; Ps. 89:30–34). The promises of it, in like manner, shew them God’s approbation of obedience, and what blessings they may expect upon the performance thereof (Lev. 26:1–14; 2 Cor. 6:16; Eph. 6:2–3; Ps. 37:11; Matt. 5:5; Ps. 19:11): although not as due to them by the law as a covenant of works (Gal. 2:16; Luke 17:10). So as, a man’s doing good, and refraining from evil, because the law encourageth to the one and detereth from the other, is no evidence of his being under the law; and not under grace (Rom. 6:12, 14; 1 Pet. 3:8–12; Ps. 34:12–16; Heb. 12:28–29).
We come now to one of the three legitimate uses of the law, which is different thing entirely from the three types of law. The first use discussed here is the help the law provides to the regenerate, informing and teaching him. (The other two uses are restraint of the godless, and evangelistic.) But first, in the minds of the godly, we must consider how the law is not to be used. The law is not, and cannot be, a ladder by which men climb to heaven. It is not a means of justification, or sanctification. It is a standard of righteousness, not a means to righteousness. With this clear, how may a gracious believer use the law?
First, it teaches the believer what God's will is. Secondly, it teaches the believer how many sinful pollutions remain in him, which need to be attended to by the grace of God. This drives them to a greater understanding of the need for Christ, just as it does with a non-believer who is being drawn into the kingdom. Third, it helps the godly to understand what their sins deserve—and not just the fact that their sins are sinful. In short, they are helped to see the magnitude of sin. Conversely, they see the fruitfulness of obedience in the promises of the law. We do not claim the promises of the law as though we had kept the covenant of works in Adam, but we claim them by faith as our portion under the covenant of grace, given in the second Adam.
In all this, we cannot say that if a man obeys the law that he is somehow, in Paul's sense "under the law," and not under grace. Legalism is not to be confounded with obedience. If obedience is legalism, then disobedience must be obedience.
7. Neither are the forementioned uses of the law contrary to the grace of the Gospel, but do sweetly comply with it (Gal. 3:21); the Spirit of Christ subduing and enabling the will of man to do that freely, and cheerfully, which the will of God, revealed in the law, requireth to be done (Ezek. 36:27; Heb. 8:10; Jer. 31:33).
Do we set aside the law in all this emphasis on grace? Not at all; rather we uphold the law.