It is common to hear of the law of God, especially in the Old Testament, divided into moral, cæremonial, and civil law. And Christian students of the Old Testament, hearing of this distinction and eager to take some parts seriously while discarding other parts that they believe to be inapplicable for our time, are often quick to classify particular statutes of God as one or another of the three. But Zacharias Ursinus, in his commentary on the Heidelberg Catechism, uses the classic threefold division differently:
Speaking of the Fourth Commandment, which of the ten is the most often cited as a reason that even the Decalogue does not apply to us today, Ursinus does not classify the commandment simply as moral or as cæremonial or as civil. Instead, he tells us that the Fourth Commandment has two parts: a commandment and a reason for it. Further, he discriminates between two parts of the commandment: ‘the one moral and perpetual, as that the Sabbath be kept holy’; and ‘the other ceremonial and temporary, as that the seventh day be kept holy’.
Ursinus shows, usefully, that the common threefold division of the law is not to classify the ordinances of God as one or another of the three, but to distinguish the various aspects of each in order to find a legitimate application. He identifies the commandment’s general æquity, the underlying præcept that, when applied in the circumstances in which the commandment was delivered, yields the commandment in the form given. This is also how we ought to examine the commandments delivered to us, that we may be faithful doers of the word and not hearers only.