In St. Paul’s Epistle to the Romans 4:13-27, he writes:
For the promise that he would be the heir of the world was not to Abraham or to his seed through the law, but through the righteousness of faith. For if those who are of the law are heirs, faith is made void and the promise made of no effect, because the law brings about wrath; for where there is no law there is no transgression. Therefore it is of faith that it might be according to grace, so that the promise might be sure to all the seed, not only to those who are of the law, but also to those who are of the faith of Abraham, who is the father of us all. (Revised Standard Version)
The Revised English Bible translates 4:13 as:
“It was not through the law that Abraham and his descendants were given the promise that the world should be their inheritance, but through righteousness that came with faith.”
St. Paul’s point is clear – his reading of the Torah is that God didn’t make His promise to the Jews through Moses, after giving Moses the Law. It was not through the Law, or in relationship to it, that God would fulfill His promise or that the Jews would inherit the world. The promise was given long before the commandments were given to Moses. The promise was given to Abraham and required a response of faith/faithfulness. As St. Paul reads the Torah, the promise of God to inherit the world ultimately is a promise about the Messiah and His eternal Kingdom. The point is clear that the promise of God, namely the Messiah, does not come through faithful adherence to the Law. The promise is given to those who respond in faith, for it is those who live by faith who are truly God’s people and the inheritors of God’s promise.
Those who continue to try to conform to some law, whether Torah or Christian tradition, are still trying to live by adherence to the law rather than by faith – they are following Moses rather than Abraham, and for St. Paul Christ is faithful like Abraham, not a law giver like Moses.