"The Law is for the Jews." What a ridiculous assertion. First of all what is a Jew? The letter J didn't even exist until recent history.
Is it a Judaean? If so would this include non believers who reside in Judea? That doesn't work.
Is it someone of the tribe of Judah? What if he doesn't believe? That doesn't work either.
Is it the Yahudim (Yah's people)? Well this I would have to agree with; but that's not the implication that is being presented by people who make this assertion. Are not Christians Yah's people? I propose that the Law is for those who are spiritual. The Law is spiritual.
For those who would insist that adherence to the law as being a matter of physical genealogy; the Law was given to more than the tribe of Judah. It was given to all 12 tribes. The Northern Tribes were carried off, scattered throughout the world, and assimilated into the Gentiles.
By this definition, are you a Jew?
Here is the first test: Account for every paternal ancestor back to the time of Jacob.
Can you do that?
Excellent!
You move on to the second round!
There were more than the descendants of Jacob who entered covenant in Egypt and/or at Sinai.
Many descendants of Jacob remained in Egypt; but many of the nations followed the El of Israel, entered covenant, and became fellow citizens of Israel. The law is for all of their generations too, as YHWH commanded.
Here is the second test: Account for every person, who is not of Jacob, who entered covenant at Egypt/Sinai, and all of their progeny.
Can you do that?
Congratulations!
Please share this information with the lost sheep; so that they don't remain lost until Messiah finds them.
You move onto the bonus round!
Now prove through all of your ancestry that you are in no way a descendant of anyone who entered covenant along with Moses.
Shabbat shalom!
I'm sure there are many "Jews" that were not physical descendants of Jacob originally. There were some proselytes even after the exodus, and likely many more over 3500 years blended into the mix. Also, the 10 tribes taken by the Assyrians did not include every single person, only the elite. The poor were left in the land. Hence Anna at Jesus' circumcision from the tribe of Asher, etc.
However, your post brings up Ezekiel 40-48 in my mind. Ezekiel's Temple has yet to be built and the land of Israel yet to be divided as written there. We also know it is impossible for scripture to fail. Therefore, these things are still to come. The land is divided up for the 12 tribes of Israel. It seems the physical descendants of Jacob remain important to God, even til the end. By extension, the Jews' distinction from Gentiles remains to the end, even after the church is eventually grafted in. How do you understand this?
As to your topic on who the Law applies to, it is a lengthy subject, but... The moral law of God has applied to every people of every generation since creation. Concerning the feasts, Temple rules and ordinances, etc. of Moses, that law applies to the children of Israel, a people God knew from the beginning would largely not believe Him. There has never been more than a remnant of believers in Israel. That gives a big clue as to why Israel was chosen! It wasn't for our/their faith.
There are two blood covenants, not one. The first blood covenant during Moses was made with the Israelites. That covenant/law applied to the Israelites, and still applies to those of Israel who do not believe God. Thus, the extra burdens. Jesus made a second blood covenant with those who do believe God, which was even extended to the Gentiles. Both covenants still apply today, but as Paul said, the unbelievers in the first covenant will not inherit with those of the second covenant. Israel was promised land on earth. The church was not because the church is not staying on the earth. The church are the Levites of the eternal kingdom, separated from the other peoples. Just as the Levites were not given any land inheritance because God Himself is their inheritance. The Temple modeled the kingdom of heaven.
Any person, including Jews, who believe in Jesus and do what He said has been freed from the first blood covenant and entered into a better blood covenant. Therefore, the rules and ordinance of Moses no longer apply. Those burdens are for the unbelievers of Israel. God's moral laws always apply, of course. It is sad to me how some Messianics, SDA's, etc. try to create a hybrid covenant between the first and second covenant. You cannot do both. Lukewarm doesn't work. Just pick one. Clinging to the first covenant is rejecting the second one.
Btw, the covenant Jesus made, generally called the new/second covenant has actually been in place from the beginning of creation. "The just will live by faith," better translated "the just, by their faith, shall live" has always applied. Long before the law of Moses. The people of old may not have known the name of Jesus, but their faith in the true God was faith in Jesus all along.