The Westminster confession of Faith says that “The infallible rule of interpretation of Scripture is the Scripture itself: and therefore, when there is a question about the true and full sense of any Scripture (which is not manifold, but one), it must be searched and known by other places that speak more clearly” (Chapter 1 Section 9). The belief that Scripture interprets Scripture has long been the position of orthodox Christianity. However, it is not uncommon for Christians to bring their own opinion to bear upon the biblical text. Pet doctrines, newspaper exegesis, current fads and so on, frequently influence our understanding of the Bible.
One passage which Christians often find perplexing is found in Matthew 17:18. Here Jesus seems to say that all aspects of the Old Covenant – moral, ceremonial and civil – will remain unchanged until the end of the world: “For truly, I say to you, until heaven and earth pass away, not an iota, not a dot, will pass from the Law until all is accomplished.” (Remember that “Law” was simply “shorthand” for what we call the Old Testament.)
If we take this literally it means that we must continue to obey the Old Covenant cultic ritual even today. After all, Jesus said that nothing will pass from the Law (the Old Testament), until heaven and earth pass away. However, even a superficial understanding of the New Testament is enough to know that this cannot be the case. For instance in Hebrews 7:11-12 we read, “now if perfection had been attainable through the Levitical priesthood (for under it the people received the law), what further need would there have been for another priest to arise after the order of Melchizedek, rather than one named after the order of Aaron? For when there is a change in the priesthood, there is necessarily a change in the law as well.”
In other words, with the new and enduring priesthood of Christ there came a change in the law (notice that the law was not abolished; only changed). Therefore we cannot take Christ’s proclamation concerning the permanence of the old covenant requirements literally and we are obliged to search the Bible in order to understand his meaning.
In the Ten Commandments we read that the Sabbath day command was given because “in six days the LORD made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the LORD blessed the Sabbath day and made it holy” (20:11). However, in the second delivery of the law prior to their entrance into the land (Deut. 5:6-22), the people were told to “remember that you were a slave in the land of Egypt, and the LORD your God brought you out from there with a mighty hand and an outstretched arm. Therefore the LORD your God commanded you to keep the Sabbath day” (5:15). Although there is a different example used in each case, the underlying reason for the Sabbath remains the same; the children of Israel were supposed to keep the Sabbath because it commemorated the beginning of a new order, a new age or era. Obviously the creation of everything out of nothing began a new order. Less obviously perhaps, the creation of a people and a nation (out of slavery), began a new order as well. Indeed, the language of creation is often used in the Bible to illustrate the beginning of a new order, just as the language of de-creation is used to express the end of an age. For instance, the new order which began with the establishment of Israel as a nation is demonstrated by God’s use of creation language in Isaiah’s prophecy, saying, “I am Jehovah your God, who divided the sea, and its waves roared; Jehovah of Hosts is His name. And I have put My Words in your mouth, and I have covered you in the shadow of My hand, that I may plant the heavens and lay the foundations of the earth, and say to Zion, You are My people” (Is. 51:15-16).