Paul and Law
Paul was a man of great learning (Acts 26:24). Peter warns that there are certain things that are hard to understand in Paul’s writings and that it is easy to misunderstand them (2 Pet 3:15-16).
Paul uses law with different meanings. He talks about law of faith (Rom 3:27), law of the husband (Rom 7:2), law of sin (Rom 7:23), law of righteousness (Rom 9:31), law of Moses (1 Cor 9:9), law of God and law of Christ (1 Cor 9:21) etc.
So, it is necessary to see clearly what law Paul is using in each context before jumping to our conclusions.
Scripture says that the Ten Commandments define sin:
“But I did not know sin EXCEPT through Law; for also I did not
know lust except the Law said, "You shall not lust." (Rom 7:7).
So, if sin was in the world from the beginning, then definitely the commandments were also very much active in the world. But:
“There was sin in the world before the Law was given; but where there
is no law, no account is kept of sins” (Rom 5:13).
Thus sin which is a breakage of the Law (1 John 3:4) was in the world before the Law was given publicly in a codified form for the first time through Moses. The holy Patriarchs knew these commandments before Moses. One example is Joseph who withstood himself from committing adultery with Potiphar’s wife because he knew adultery was sin against God (Gen 39:9). He knew the Ten Commandments!
However, in the case of those who didn’t know God and His Law, their sins are not counted in the ultimate sense; their sins are not charged, as per Rom 5:13.
What law came after 430 years
Then what about the law that came after 430 years? Definitely this law cannot be the Ten Commandments!
Paul explains himself:
This law was given because of transgressions (Gal 3:19); this law had validity only until the Sacrifice of Christ (same verse); it was given through a mediator (same verse); it worked as a trainer until Christ (verse 24).
Let us think logically:
The spiritual law of Ten Commandments defines sin (Rom 7:7), “for sin is the transgression of the Law” (1 John 3:4).
So, the law that was given because of transgression/sin should be another type of law!
Yes, Paul calls this set of law as “the works of law” that was given because of the breaking of the Ten Commandments!
Christ had to sacrifice Himself because people broke God’s spiritual law (sin). So the works of law was to continue only until Christ, but the spiritual law is eternal. The works of law was like a trainer for a time until Christ.
The spiritual law of Ten Commandments was given directly by God to the people (Deut 5:4). There was no mediator; no, not even Moses was between God and the people, but the works of law was given through a mediator.
The works of law was given through the Levitical priesthood. But when Jesus Christ became an eternal High Priest in the order of Melchizedek, the works of law ceased to exist.
“Truly, then, if perfection was through the Levitical priestly office
(for the people had been given Law under it), why yet was there
need for another priest to arise according to the order of Melchizedek
and not to be called according to the order of Aaron? For the priestly
office having been changed, of necessity a change of LAW also
occurs” (Heb 7:11-12).
So, we see that the “mediator” was the Levitical priesthood! When the High Priest changed from the line of Aaron to the order of Melchizedek, the office and function of Levi tribe (including Aaron) ceased to function.
What was their function?
Primarily ,it was to provide continuous sacrifices for the sins of the people. But Christ gave the one and only perfect Sacrifice for all time. Levi no longer needs to sacrifice! So, works of law ceased to exist as a trainer.
Conclusion
The law that came after 430 years was not the Ten Commandments. It was the law of animal sacrifices that was entrusted to the Levitical priesthood that came with the line of Aaron.
The Ten Commandments never ceased to exist. If it did, then there will not be any sin in the world! But the animal sacrifices (a shadow of Christ) under the Levitical priesthood ceased to function after Christ.