The main Christian virtue taught by Paul in his Epistle to Philemon is

The main Christian virtue taught by Paul in his Epistle to Philemon is forgiveness. In the letter, Paul writes to Philemon, a Christian slave owner, about his runaway slave Onesimus who has become a Christian. Paul urges Philemon to forgive Onesimus and to receive him back not as a slave, but as a brother in Christ. Paul emphasizes the importance of forgiveness and reconciliation between Christians, and highlights the transformative power of the gospel in bringing about forgiveness and unity between believers.