The Joy in Christ' Righteousness

Paul encourages the Philippians to rejoice in the Lord and warns them against false teachers who put confidence in the flesh. He contrasts this with his own background and achievements, which he now considers worthless compared to knowing Christ. The surpassing value of knowing Jesus and gaining righteousness through faith in Him is what ultimately gives the believer a deeper joy. Paul is able to consider all of his works as rubbish because he has experienced something supremely greater.