28 For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. 29 But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God.
The book of Romans is to the church at Rome. This church has Jewish Christians & non-Jewish Christians. But this phrase in particular is Paul calling out the Jews of his day who would rely on Jesus as well as their circumcision and their rule following.
His point is clear: to be saved & in right relationship with God, the outward & physical is not of value, instead it is the inward, the Spirit of God in us, the new heart, that is what is important. The inward change is what produces the outward change. Not the other way around.
Do the inward work & the outward work will happen. Seek Jesus in the Word. Pray often. Be vigilant in knowing Jesus & what he is like and who he is. Fight your thoughts. Fight your wandering thoughts with the promises of Jesus. That is what changes you, that is what we fight against.
Give us eyes to see Lord, I pray that we would not hope in anything but in the work of Jesus on the Cross. That we would value you this and that would produce in us the good fruit. May we not produce our own fruit, but rather may we trust in you to produce that in us.