Paul wrote this letter to the Philippians to express his appreciation for their support and concern for him while he was imprisoned. He discusses his joy despite difficulties and encourages the Philippians to remain unified and steadfast in their faith. Paul provides the examples of Jesus Christ's humility, Timothy's faithful service, and Epaphroditus's dedication as models to follow. He exhorts the Philippians to think on things that are virtuous and praiseworthy in order to experience the peace of God. Throughout the letter, Paul emphasizes maintaining a positive attitude and finding joy in all circumstances through one's relationship with Christ.