First is the position that all the Old Testament law is still directly applicable and should be obeyed, although I'm not aware of anyone who actually believes this:
This is said to be the position of Theonomists, but the writings of Rushdoony, North, and Bahnsen, and their disciples actually do a lot of adapting of the Old Testament law rather than woodenly applying all of it.
Messianic Jews who practice elements of the ceremonial law still don't see it as binding.
There are certain cult groups like the Seventh Day Adventists and Oneness Pentecostals which obligate Christians to following questionable parts of Old Testament law to varying degrees.
There is also in the Dispensational camp the belief that although Christians today are not obligated, everybody will be obligated to Old Testament ceremonial laws once Jesus returns, including a return to sacrificing animals, which I believe is blasphemous.
On the opposite side of the spectrum are those who believe that all the laws in the Old Testament are irrelevant.
Marcion was an early church father who rejected the authority of the O.T., as did Chrysostom and some of the lesser-known church fathers from Antioch.
It showed up again in some of the radical wing of the Reformation, and in the modern Liberal church (in people like Bultmann), and in many post-denominational churches as well.
The New Unger's Bible Dictionary, for instance says, in its article on Law, “This Mosaic system, including the Ten Commandments as a way of life came to an end with the death of Christ (John 1:17; Rom. 10:4). The Mosaic age was preceded (Ex. 19:4) and followed (John 1:17) by grace.” I believe that Unger misunderstood the meaning of the Greek word ΤΕΛΟΣ1 and was seriously mistaken to indicate that Israelites were saved by some other means than by God's grace.
Other Christians have wisely taken a less-polarized stance, but on the principle of Jeremiah 31:31ff, “I will make a new covenant with you, not like the old covenant I gave your fathers.” They still see a basic discontinuity between the Old and New Testament and only accept the law of Christ in the New Testament as having significance and binding force.
People in this less-polarized camp would include Luther,
the Pietist traditions like the Mennonites,
and, to a large extent, the Baptist tradition.
(I realize that there are always exceptions when one makes such broad generalizations, but I'm trying to paint a big picture in a short time, so I'm using broad strokes.)
The fourth category, which is a second less-polarized stance, would be
represented by church fathers like Origen and other Alexandrian church fathers
and by Calvin in the Reformation and the Puritans
and much of the Presbyterian and Reformed tradition today.
These see essential continuity throughout the history of God's dealings with man,
for instance the fact that the covenants with Noah, Abraham, Moses, David, and the New Covenant are all called “the eternal covenant” in the Bible2.
The differences which clearly existed in the progressive installments of God's relationship with mankind were not meant to conflict but to complement one another.
This is my position, and I'd like to flesh that out in regards to Leviticus 3:17,
but before I do that, I want to mention that I was really sharpened in my position by reading Christopher Wright's book Walking in the Ways of the Lord: The Ethical Authority of the Old Testament.
In this book, Wright suggests what he calls a “paradigmatic” way of looking at the laws given to the nation of Israel. He wrote, “I take 2 Timothy 3:15-17 as an axiomatic starting point. This text affirms that the Old Testament law is part of the Scriptures, which, being God-breathed, are salvifically effective and ethically relevant. The question, therefore, is not whether the Old Testament law has authority and relevance for us as Christians, but how that given authority is to be... applied... Exodus 19:1-6 is a key text... it gives to Israel an identity and role as a priestly and holy people in the midst of 'all the nations' ...The law was not explicitly and consciously applied to the nations. But that does not mean it was irrelevant to them. Rather the law was given to Israel to live as a model, as a 'light to the nations' [Isaiah 42:6; 49:6; 60:3] … That overall social shape, with its legal and institutional structures, ethical norms, and values and theological undergirding, thus becomes the model or paradigm intended to have a relevance and application beyond the geographical, historical, and cultural borders of Israel itself... When dealing with any particular law, we need to ask how it related to and functioned within the overall social system of Israel... Whose interests was this law trying to protect? Whose power was it trying to restrict? What kind of behavior did it encourage or discourage? What... state of affairs was it trying to promote or prevent? … Moving from the Old Testament world back to our own, we can ask a parallel set of questions about our context... how the objectives of Old Testament laws can be achieved...” (p.111-116)
D
r. Wright illustrated this paradigmatic use of Old Testament law with this diagram: You see the three subjects of the law as a triangle: God, man, and creation. God defines these three relationships through His law. In the top triangle, the Mosaic law is represented as perfectly defining these three relationships for Israel at a certain period of time. The next inner triangle represents the New Testament church; it encompasses the Old Testament triangle but with the addition of the laws Jesus gave us. These two triangles of law in the Bible flesh out a way of relating to God, to man, and to creation in a way that is very detailed and concrete in its time and place. They therefore give us paradigms for seeing ideals applicable to any time and place – of how people should relate to God, to each other, and to the earth. (And also in these paradigms, we see types and symbols of what the order of things will be like in heaven.)