“A man is not a Jew if he is only one outwardly, nor is circumcision merely outward and physical. No, a man is a Jew if he is one inwardly; and circumcision is circumcision of the heart, by the Spirit, not by the written code. Such a man’s praise is not from men, but from God” (Rom 2:28-29).
Paul is NOT teaching here that a Gentile who has a heart for God is a Jew!—Nor is he teaching that a Jew who doesn’t have a heart for God is not really Jewish. This statement is connected to a broader teaching about passing judgment—and the tendency on the part of many people to judge others without taking into consideration their own behavior.
Paul is saying that we should be careful not to criticize others for behavior that we engage in ourselves. For Yeshua, the Rabbis and for Paul, this was hypocrisy! And, it involves the “disconnect” between who we are on the “inside” and what we pretend to be on the “outside.” This pretense can take many forms and is often the result of a sense that we are superior to others because of the religious activities that we engage in—especially if others do not.
Paul’s point? That true spirituality is about the “inside” and the “outside” together. As when the former reflects the latter, and vice-versa. It is the connection between “form” and “substance,” “shadow” and “light”—the circumcision of both flesh and heart—NEVER the one without the other.