Paul is reminding the Jews, that God is not partial.

God looks at the heart, which can't be hidden.

Those not circumcised outwardly, but follow the law, become a law unto themselves, because they do the right things.

Paul lets the Jews know that they are suppose to be the teachers and the doers of the law.

He is a Jew who is one inwardly, not by the letter of the law, and his praise is not from men, but from God.