Paul was a Pharisee before his Damascus experience.(Acts 23:6, 26:5, Philippians 3:5.) Interestingly, Paul keeps the identify of "Pharisee" with him. He never abandons it. By the time Paul speaks in Acts 23 and 26, he has already had his Damascus experience, so he should have dropped his Pharisee title. But he kept it when he is questioned in Acts.
Why did Paul keep this title? Is he unaware Jesus called the Pharisees hypocrites?(Matthew 23:13, 14, 15, 25, 27, 29, Luke 11:44) Or about the time Jesus said,
Jesus did not think well of Pharisees, yet Paul thought it was acceptable to keep this title. Since Paul thought it acceptable to keep this, we should heed Jesus's warning:
Leaven is an agent put in bread (or other doughs) that ferments it, causing it to raise. During fermentation, the leaven spreads across the dough, so it is impossible to separate the leaven from the dough. In the same fashion, Jesus was saying, "Beware of the doctrine of the Pharisees." The doctrine of the Pharisees would ruin the rest of the doctrine of Christ, making it impossible to determine truth from lies.
Value of this Evidence
This is not indefensible evidence of Paul being a false apostle, perhaps Paul is just a coward, or did not realize how bad it was to claim to be a Pharisee.