If someone else thinks they have reasons to put confidence in the flesh, I have more: circumcised on the eighth day, of the people of Israel, of the tribe of Benjamin, a Hebrew of Hebrews; in regard to the law, a Pharisee; as for zeal, persecuting the church; as for righteousness based on the law, faultless.
Here, Paul seems to be issuing a challenge of sorts, as if to say that if anyone could claim salvation by being a Jew, it is Paul, but Paul claims salvation in Christ alone. He gives a brief summary of his resume as a Jew; it is an impressive one. Thus, of all people, Paul the Jew among Jews, has no confidence in the old ways, for he knows that only Jesus Christ can take away sin and give the gift of eternal life.
If we were to extend his reasoning a little bit, we might ask a question like, “What of this world can possibly save you from destruction? Your fortune, your possessions, your education and accomplishments?”
No, none of these things can take away sin, and without that, there is only destruction. It is no wonder, then, that Paul began this passage by encouraging the people to rejoice in the Lord always.