The whole Law. Let me explain why.
Israel have a Covenant of Promise, made 430 years earlier that the Covenant of Law at Horeb. This first Covenant PROMISES to give the seed of Abraham a Land. But once they came into this Land they were to (i) host the presence of the Almighty, and (ii) live a certain way before the nations surrounding them. The Covenant of Law primarily caused Israel to be ritually clean to serve a Holy God. Secondly, it cased them to live in a way that did not pollute the earth as the Canaanites did, and thirdly it was a testimony of God's righteousness and subsequent blessing before the Nations.
But Israel did not keep the Law. They were UN-holy before a Holy God, they defiled the Land with idols, sexual offenses and violence, especially against the weak, and they displayed Satan's unrighteousness rather than God's righteousness. They took the habits and traditions of the heathen around them. God chastised and chastised them and finally ejected them from the Land.
The New Testament presents a totally different scene. Here, God raises up a People, not to dwell WITH them, but to dwell IN them. No longer would the Law be enough to make a man righteous enough to host a Holy God LIVING IN HIM. It is one thing to be near God. He can always put up a Curtian, or Veil, but to have Him IN us is totally another thing. So God, to deal with the problem of the flesh, does TWO things;
- He sends His Son Jesus to die for the sins of men so that He could have judicial grounds to forgive our offenses
- He sends His Son Jesus to be a Man under Law to fulfill it and establish a perfect righteousness for a Man
Then, Jehovah takes the sinful and unclean man and APPLIES BOTH to him. If a man believes in Jesus and what He did, and confesses it, God IMPUTES Christ's substitutionary death and IMPUTES Christ's righteous life to the believer. Then, God, to make sure He is not offended, counts the believer to be IN Christ and thus the believer was, IN Christ, killed with Christ (Rom.6:1-6; Gal.2:20). Although he is still alive, by being in Christ, God causes the believer's unclean flesh to be annulled and dead. There is NOTHING the Christian must add to this to be holy before God. If the Christian tries to do something to be holy, he is, in effect, saying that Christ's life was not good enough, and God was wrong to impute Christ's righteousness to him, seeing that he can establish a better one himself. And THAT, is why the language of Galatians is so strong. Any man or woman who has believed in Christ, and who returns to the Law, is declaring that HIS/HER efforts are better than Christ's.
But there is another problem. The New Man that God raised up is made from EX-Gentiles and Ex-Jews (the "TWO" of Ephesians 2:15). But the Law of Moses forbids the Jew from having any relations with the Gentiles. This would destroy the unity in the Church that Jesus prayed for in John 17:21-23. So our Lord Jesus takes the Law onto the cross with Him. This means that if you are a Jew, and REJECT Jesus, the Law is still valid for you. If you are an EX-Jew who has embraced the work and Person of Christ, the Law is dead, gone, abolished. Why do I say "EX-Jew?" It is because 2nd Corinthians 5:17 says that if you are IN Christ, your past is wiped out. Everything is New! So Galatians 3:28 and Colossians 3:11 show that there is NO ETHNICITY in the New Man. There are only EX-Jews and EX-Gentiles in the New Man.
The objection will at once arise that Israel are under another Covenant - that made with Abraham for the Land of Canaan, AND ETHNICITY IS EVERYTHING - seeing as it entitles one to a Covenant and its promises. This, God takes care of in the same sovereign way. By making us IN Christ. Galatians 3:28, as shown above, denies any ethnicity in the New Man. But the very next verse, verse 29 shows how by being Christ's - Who is the Promised Seed of Abraham (v.16) - we are made HEIRS. That is, those in Christ have their ethnicity wiped out, but get a NEW ONE - the Top and Chief Seed of Abraham, Jesus. And not only are both believing Jew and believing Gentile made seed of Abraham by being Christ's, but the Promise is expanded from Canaan to the "the whole world" (Rom.4:13).
But now that Law is abolished, how shall the Christian live. Romans 8 tells us. Christ has come to live in us. He is that Spirit of John 7:39 and 1st Corinthians 15:45. He speaks from our spirit where He dwells - on ALL MATTERS. Shall you kill. Be lead by the Spirit in your spirit. Should you forgive a certain man. Ask the Spirit in your spirit. How long should your hair be? Ask the Spirit. Should you be a missionary, or which woman should you marry? Ask the Spirit. Are you allowed to watch TV and/or drive a Mercedes Benz. Can you have a whiskey on your birthday? Is my dress too long or too short? AS THE SPIRIT IN YOUR SPIRIT. In this way, your LIFE will be dictated to by THE LIFE of Christ IN YOU. To one he allows 20 failures and then chastises. To another He only allows 5. To one He gives 10 talents, to another He gives 5. Christ, together with His perfect life, dwells in you and that is your LAW - the "Law of LIFE in Christ Jesus". Moses gave about 20 Laws. The New Testament has 2,400 commands. Your daily life over ten years might require 5,000 answers. They should all be in accordance with Christ IN YOU.
As Summary;
The Law is good, spiritual and God-given (Rom.7)
The Law is ONLY GIVEN TO ISRAEL
The Law could not make a man holy because the man was weak
God allowed His Son to be under Law and establish a perfect righteousness that a fallen man could not
God IMPUTES this righteousness to a Believer
The Jew is still under this Law, but the Believer is not
Any Believer who places him/herself under the Law is saying that Christ's life was inadequate for righteousness
Any Believer who says this defies God Who has approved this righteousness
Any believer who defies God's appraisal of Christ insults both God and Jesus
Any believer who uses Law has (i) fallen from GRACE, and (ii) made the work of Christ OF NONE EFFECT
No man can be justified by Law