Romans 2:29

but he is. Jew who is one inwardly; and circumcision is that of the heart, in the spirit not in the letter; whose praise is not of men, but of God.

Paul is affirming that there was also more to being. 'Jew' than mere physical requirements (ancestry and circumcision). There is nothing new about 'heart circumcision' (Deuteronomy 10:15; Deuteronomy 30:5; Jeremiah 2:4; Jeremiah 2:25).

'spirit not in the letter' -this doesn't refer to some 'unspoken, inferred, between the lines law' in the Law of God. God expected obedience, and yet God always wanted obedience from the heart. People that obey God not because of rote or tradition, but because they want to. These are the type of people that serve God because they desire His approval and love rather than the praise of men.

CHAPTER TWO REMINDED THE JEW:

1. They had sinned against the knowledge they had of God too, just like the Gentile. Their lives were also inconsistent with the knowledge of right and wrong they possessed. And hence they stood just as guilty as those mentioned in chapter one. Ouch!

2. If one can be right with God on the basis of 'law-keeping' (as opposed to obedience and forgiveness), then the Gentile stood on the same ground with the Jew! For both had 'law'.

3. Circumcision was pointless without obedience.

4. They were not the 'elite', but they had been the 'elect'. They were supposed to show other nations how to live, but for the most part they had only turned others off from God by their inconsistent and hypocritical conduct. And the lives of some Gentiles even put them to shame. (Acts 10:1 ff)