The law was given through Moses; grace and truth came through Jesus Christ. NIV These two statements by John are not contrasting but rather mutually reinforcing. Moses was a shadow of the Messiah who listened to God and brought the Word of God to the Chosen People. Jesus is the Messiah and the Word of God, who by both being and living the Word has shown all people the grace and truth of the law.
Paul seems to throw out the Law. Now that faith has come, we are no longer under the supervision of the law. NIV But Paul did not throw away the Law. What he said, when we look at all his writings, was that love frees us from the rigidness of the Law. Love is the intent of the Law, so if we love we will not break the Law.
For non-Jews the Law of Love is all that is needed. A Greek can still be a Greek. A Roman can still be a Roman. We do not give up being who we are, we simply focus who we are on God.
Paul goes on in chapter four of his letter to explain that we become children of God. That does change us. We are no longer only Hebrew, Greek or Roman. We now have dual citizenship. I am both Roman and Heavenly.
That means that I am bound by the Word of God, but I follow the rules of my earthly kingdom only when they do not conflict with that Word. All too often that puts me at odds with the earthly kingdom. When that happens I must be willing to accept the punishment the earthly rulers give me. I am a citizen.
But that punishment, even death, pales when compared with the rewards of being a son of God.
Be righteous and do good.