Paul (formerly called Saul) was “a Hebrew of Hebrews”—the product of fine Jewish ancestry all the way back to Benjamin, Jacob, Isaac and Abraham (2 Corinthians 11:22; Romans 11:1). As you read the letters of Paul, you find frequent references to the law of Moses (often simply called “the law”). Paul belonged to the Pharisees, an elite sect that followed the law strictly. They viewed the law as their ladder to God. Paul climbed the ladder better than most of his peers (Acts 22:3; 23:6; 26:4-5; Galatians 1:13-14). Paul’s religion depended on many fleshly things: his own effort at keeping rules and regulations, his earthly ancestry, and the fleshly mark of circumcision. That is why Paul called that type of religion “confidence in the flesh.” Paul felt confident that his fleshly credentials made him acceptable to God.
If anyone else thinks he has reason for 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; as to the law, a Pharisee; as to zeal, a persecutor of the church; as to righteousness under the law, blameless (Philippians 3:4-6).
Paul seemed to excel at “righteousness under the law.” He was “zealous for God” (Acts 22:3). He lived before God “in all good conscience” (Acts 23:1). He was making great progress along the road of Judaism, and he sincerely believed this road led to God.