Paul says in Romans 7:14 that “the law is holy, and the commandment is holy and righteous and good.” Our attitude towards God’s law ought to mimic the Apostle Paul’s positive attitude. A very important interpretive principle should guide and direct our understanding and our application of God’s law to our lives and the lives of others, a principle that is often neglected or dismissed in this day and age: the principle of periodicity.

The Princeton scholar, Geerhardus Vos, summed this up well at the beginning of his book on Biblical Theology by stating:

The method of Biblical Theology is in the main determined by the principle of historic progression. Hence the division of the course of revelation into certain periods. Whatever may be the modern tendency towards eliminating the principle of periodicity from historical science, it remains certain that God in the unfolding of revelation has regularly employed this principle. From this it follows that the periods should not be determined at random, or according to subjective preference, but in strict agreement with the lines of cleavage drawn by revelation itself. The Bible is, as it were, conscious of its own organism; it feels, what we cannot always say of ourselves, its own anatomy. The principle of successive Berith-makings (Covenant-makings), as marking the introduction of new periods, plays a large role in this, and should be carefully heeded.(1)

Therefore, one of the foundational principles of correctly interpreting the Scriptures is that one respects and listens to the covenantal context of any given passage in Scripture when the meaning is being interpreted and application is made. To better understand the law, one must apply the principle of periodicity in studying the function of the law in the pre-fall, post-fall, and New Testament eras.

The Principle of Periodicity and the Pre-Fall era

First, in the Garden of Eden, Adam was under a covenant of works: there was law. The Westminster Confession of Faith (WCF) states, “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 . . .” (19.1). In that garden the tree of life and the testing tree of the knowledge of good and evil contained the seeds of the gospel. The tree of life was essentially a symbol of the best life that awaited Adam if he were to pass his probation in that garden.(2) The tree of the knowledge of good and evil signified the law because it was given as a “trial of obedience and by sin (no less than that) [was] made the occasion of death and the minister of condemnation.” (3)

Recognizing the role and application of the law as conditioned by the covenantal context is especially important in the differences evidenced between the pre-fall situation and that situation following the fall of mankind. For example, works play a fundamentally different role in the pre-fall covenant, a covenant of works, than they do in the post-fall covenantal period, in the covenant of grace. In the pre-fall covenant, works function as a condition of acquiring life; in the post-fall covenant they follow the act of justification and demonstrate that one has life in the Son.(4)

Let’s now turn our attention to the periods after the fall.

The Principle of Periodicity and the Post-Fall era

In the post-fall era, law remained in effect. The WCF states, “This law, after his [Adam’s] fall, continued to be a perfect rule of righteousness; and, as such, was delivered by God upon Mount Sinai . . .” (19.2).

First, notice that the law remained in effect, a law that even from the period of Adam to Moses “obligated people personally and rendered them guilty.”(5) The similarity between the periods lies in the fact that the law still requires perfect obedience; the distinction; however, with the advent of the covenant of grace in the post-fall era lies in the fact that the law now has a different function. As Dr. Sam Bolton, a prebend of Westminster and chaplain to Charles II, eloquently reminded us about the shift in the function of the law, “The law [now] sends us to the gospel for our justification; the gospel sends us to the law to frame our way of life.”(6) Our obedience to the law can no longer acquire life for us.

Notice also, in the above citation from the WCF, that there is a connection made between what happened in the garden and what happened at Sinai. There is continuity between the two periods, though differences remain. In Israel of the Old Testament, we have not just the moral law, but now the ceremonial and judicial laws, applying to the theocratic people of God in Israel. The WCF states:

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; and partly, holding forth divers instructions of moral duties. All which ceremonial laws are now abrogated, under the New Testament. To them also, as a body politic, He gave sundry judicial law, which expired together with the state of that people; not obliging any other now, further than the general equity thereof may require (19.3-4).

According to the WCF, as the people of God progress towards the New Testament period, the function and application of the ceremonial and judicial laws change; indeed, they are abrogated, expire (that is, die out), become extinct, cease, and come to an end. The ceremonial and judicial laws given to the state of Israel during the time of the theocracy were not meant to be applied forever (further than general equity requires), according to the WCF. Reformed theologians have recognized and respected this principle for years—for God could sanction wise laws at one time and in one nation for one purpose and then for certain reasons not sanction them for another according to his own prerogative.(7)

The reader should consider two similar points made by John Calvin in his Institutes (II. 7.15 & II. 7.16) where he discusses the changes in the use and effects of the various aspects of God’s ceremonial and judicial laws assigned to Israel as a body politic—in other words, according to what time period, or more specifically, what covenantal era the people of God are living in. Commenting on the points made by Calvin, Paul Helm, a professor of philosophy and theology, sums up:

What these nuances reveal [in the passages from the Institutes] is that Calvin’s approach to ethics, or the part played by the revealed law of God in ethics, is heavily influenced by his understanding of the progress of revelation and of the successive eras of God’s unfolding redemptive purposes. This makes a straight comparison between his views and those of the medievals, who understood divine law in a rather more formal and abstract way, somewhat difficult. (8)

Consequently, the WCF and reformed luminaries, such as Calvin and Vos, have maintained the importance of recognizing the principle of periodicity for a correct understanding and application of biblical law. Now let us turn to the NT in order to see how our Lord himself applies this same principle of periodicity.

The Principle of Periodicity and the New Testament era

This shift to the New Testament period raises the important issue of the interpretation of Matthew 5:17-20. In Matthew 5:17, our Lord says in his Sermon on the Mount, “Do not think that I came to abolish the Law or the Prophets; I did not come to abolish, but to fulfill.”

To the original audience, this would have been a most jarring message! Although our Lord’s message would have been penetrating and incisive—the real surprise is the teacher Himself! The uniqueness of this message is expressed by a Jewish author writing about the Sermon on the Mount:

Yes, I would have been astonished. Here is a Torah-teacher [referring to Jesus] who says in his own name what the Torah says in God’s name. It is one thing to say on one’s own how a basic teaching of the Torah shapes the everyday . . . It is quite another to say that the Torah says one thing, but I say . . . , then to announce in one’s own name what God set forth at Sinai . . . For what kind of torah is it that improves upon the teachings of the Torah without acknowledging the source – and it is God who is the source of those teachings? I am troubled not so much by the message, though I might take exception to this or that, as I am by the messenger.(9)

The messenger Jesus, as the incarnate Lord, may legitimately change or adjust the constitution of Israel. As is well known, the Pharisees (and the Rabbis that followed), punctiliously interpreted and observed the law, even suggesting that protective manmade boundaries should be placed around the law for the protection of the Torah so that people would not commit violations against the Torah.(10) Jesus’ point, however, in the Sermon on the Mount, even when he comments on “not one iota or mark will pass away from the law” (Matthew 5:18), seems to be saying that the law should be definitively interpreted as he, the Messiah, says it should be not as the Pharisees do.


This brief article has demonstrated that not only Geerhardus Vos, the WCF, nor John Calvin alone have considered the principle of periodicity an extremely important function of biblical interpretation with respect to the understanding and application of the law of God. But most importantly, our Lord’s own authoritative words constituted and consecrated it as an essential principle for rightly understanding his law and its application according to particular covenantal eras. No one may understand God’s truth or the application of his word to the world in which we live without reverence and humility. May our God grant courage and wisdom to his people to take to heart this principle while endeavoring to understand and apply this complex and challenging aspect of God’s word.