Hee was not a Jew that is one outwarde:

For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh;
But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God.

Romans 2:28-29:

Later Paul says,

Therefore we conclude that a man is justified by faith without the deeds of the Law;
Is he the God of the Jews only? is he not also of the Gentiles? Yes, of the Gentiles also;
Seeing it is one God, which shall justify the circumcision by faith, and uncircumcision through faith.

Romans 3:28-30.