First thing you've got to do when Old Testament law arises is ask what laws are you talking about? You have to look at Old Testament law and divide it up because some of the laws are abiding and remaining, still relevant; others have passed away. The traditional way that it's been done is you divide it into three. This isn't just something men and women have invented. I believe the New Testament guides us to do this.
You've got ceremonial law, ritual law, the sacrifices, the feasts, the tabernacle, the temple. Jesus says, "I am all of that. It's done away with. I'm the fulfillment of all that that pictures. I'm the sacrifice. I'm the priest. I'm the tabernacle. I'm the temple. I'm the Passover. I'm the Feast of First Fruits. It's gone. Ceremonial law: finished, because I am the Christ of the ceremonies. We don't need the pictures anymore. The reality's here."
Then you've got what's usually called judicial law or civil law, laws that were given for Israel, a unique nation and a unique place at a unique time. God gave them special laws to preserve them, to maintain them as a nation, to separate them from other nations, to make sure they wouldn't just be amalgamated until the purpose of that nation was fulfilled, which was to be the nation from which the Messiah, the Christ would come. Once he has come, the need for all these laws that separated Israel, preserved Israel, gave them that unique status were really no longer relevant.
There are model principles, there's wisdom in these laws that we can look at and say, "Hey, that's useful. That's helpful." We don't need, for example, the penalties, the extreme penalties that were used to really make sure this nation would be preserved until Christ came. Ceremonial law: fulfilled. Judicial law: no longer necessary apart from what's wise. Then you have the model law of God summarized in the ten commandments. I think that's usually what people are asking about when they say, "Do I need to obey Old Testament law?" I think that you have to take people to how that law was revealed. People often are like, "Law. Legalism." It was revealed in the context of grace.
The whole ten commandments begin with, "I am the Lord. You're God," so this relationship. Who brought you out of the land of Egypt? There's redemption. Therefore, you shall have no other gods before me. He's saying, "Look, there's relationship already. Redemption's been accomplished. Now here are some rules to help you show your gratitude and your obedience, your gratitude and your thankfulness for this relationship and this redemption." That's how Jesus puts it as well. He says, "If you love me, this relationship, keep my commandments." Yes. The model law is still relevant, we are to obey it, but why is the question. It's not to get redemption or get relationship. There's no way we can do that. It's to show our gratitude for that redemption and that relationship. "If you love me, keep my commandments."
Under law, or under grace? David Murray explains whether New Testament Christians must obey Old Testament law.