I think we need to be careful of the idea that the New Covenant, after the model of the covenant with Abraham, is something that requires no response, or just the inward assent of faith, as opposed to a moral works oriented covenant of law. I don’t think that this is what Paul was primarily driving at.
The works in question were Jewish deeds of Torah, circumcision, kosher, holy time observance, the outward identifiers of belonging to the covenant people. The NT controversy centered around circumcision, as the entrance sign of belonging, and of taking up life under Torah… to become fully Jewish, in addition to faith in Jesus as messiah.
Paul was saying that Gentiles, who believed in/gave allegiance to and joined up with messiah, became his followers and received his powerful transforming spirit, were not required to be circumcised, and live life under the Torah. They did not need to become Torah observant Jews. In fact, the time of the Torah was up. It was temporary, pointing to what has now begun, new covenant/new creation in the messiah.
This is why Paul points to the idea that Abraham’s faith in God was counted as righteousness/faithfulness to the covenant, before he was circumcised. He was the model of God revealing his own righteousness/covenant faithfulness in the messiah to faith, totally separate from Torah observance. Inclusion into God’s new covenant people was the same for Jews and Gentiles…faith in the messiah.
But, that faith was and is an active response. It was not only believing the promises of God in Christ, it was joining with Christ in loyalty to him. It was becoming a disciple, to follow him where he would lead. It was living a life together in the spirit in love, that is actually obedience to Jesus as the lord of self giving love.
This faith is not perfectionism, as seen in Adventist circles, but it is a way of life to which they were and we are still called. The life of forgiven messiah people, who individually and together are his new creation in this world.