Everything Paul did was attempting to explain OT prophecy to people who didn't understand it, or had never read it, because they didn't know it was about them. They were "lost sheep." It isn't complicated; we just make it that way.

But no, I do not follow the law, because the purpose of the law isn't to be followed, but to demonstrate that it cannot be followed. I've explained this to you before. a "jew" believes that anyone can be Godly by following the law, even though the law was never given to/meant for them. They believe this because they are the people it was never meant for. Paul explains that this is folly. You cannot just follow the law and be righteous, because no one can follow the law, whether an Israelite or non-Israelite. Which is why salvation is through faith. And the verse (or section of Romans) you quote explicitly says that the mercy is for the descendants of Abraham.

Abraham had many descendants who did not follow the law, or worship Yahweh. At least 80% if not more. And yet they are still going to be saved because of the faith Abraham had in Yahweh when Yahweh made his covenants with Abraham. If all it took to be "saved" was following the law, then there is no purpose in faith, and if faith can just be had by anyone, then what purpose are the promises. Modern eschatology makes light of extremely important and powerful events that took place for a specific reason, for a specific people.