Are Christians supposed to keep the Old Testament law?

The whole of the Old Testament Law has different parts, some say three: The Civil law, the Priestly law, and the Moral law. The Civil law deals with things like the punishment of murderers, thieves, and property disputes. The Priestly law deals with what the Old Testament priests were obligated to do regarding blood sacrifices. The Moral law is things like do not murder, do not steal, do not commit adultery, etc.

Some of these laws we Christians do not have to keep, but others we do.  For example, we are not required to keep the Old Testament sacrificial laws about offering animals on the altars. That has been fulfilled in Christ and is no longer a necessity. On the other hand, God says do not murder (Exodus 20:13) or commit adultery (Exodus 20:14), etc.  These moral laws are still in effect, and we are obligated to keep them.

In addition, Jesus quoted two verses of the Old Testament as valid laws that Christians are supposed to keep. In Matthew, Jesus said . . .

“‘You shall love the Lord your God with all your heart, and with all your soul, and with all your mind.”  38 “This is the great and foremost commandment. 39 “The second is like it, ‘you shall love your neighbor as yourself.’ 40 “On these two commandments depend the whole Law and the Prophets,” (Matthew 22:37-40).

The first quote about loving God is from Deuteronomy 6:5 and the second quote about loving your neighbor is from Leviticus 19:18. Both of these are from the Pentateuch, which are the first five books of the Old Testament, and are collectively known as “The Law.” So, Christians are obligated to keep them.

There are certain aspects of The Law that were clearly meant only for Israel during the Old Testament, before the arrival of Jesus the Messiah.

• “Speak to the sons of Israel, saying, ‘You shall not eat any fat from an ox, a sheep or a goat,” (Leviticus 7:23).
• “Speak to the sons of Israel, saying: ‘When a woman gives birth and bears a male child, then she shall be unclean for seven days, as in the days of her menstruation she shall be unclean,” (Leviticus 12:2).
•  “Speak to the sons of Israel and say to them, ‘When you enter the land which I am going to give to you and reap its harvest, then you shall bring in the sheaf of the first fruits of your harvest to the priest. 11 ‘He shall wave the sheaf before the LORD for you to be accepted; on the day after the Sabbath the priest shall wave it,” (Leviticus 23:11).

Obviously those things directed only at Israel are not for Christians today.

The Law cannot save us

Furthermore, Christians are not required to keep the Old Testament law in order to be saved because we are no longer under The Law (Rom. 6:14-15).

• “For sin shall not be master over you, for you are not under law but under grace,” (Rom. 6:14).
• “Therefore, my brethren, you also were made to die to The Law through the body of Christ, so that you might be joined to another, to Him who was raised from the dead, in order that we might bear fruit for God,” (Rom. 7:4).

Though The Law is good, but we are not able to keep it sufficiently. The Old Testament standard of keeping The Law is perfection (Deuteronomy 27:26, Galatians 3:10). So, we cannot be saved by keeping the commandments because were not capable of doing them perfectly. This is why Jesus came to this world, was made under The Law (Galatians 4:4), and fulfilled it perfectly having never sinned (1 Peter 2:22).

So, though we are obligated to not lie, steal, commit adultery, etc., abiding by these do not keep us saved nor do they get us saved.  We keep them to honor God as Christians.