"The book of Philemon is not a book about slavery. Its purpose is to teach forgiveness and acceptance. Paul is sending Onesimus back to Philemon not to be his slave, but to assist him in his work to spread faith in the Protagonist.
Philemon is encouraged to receive a runaway slave by the name of Onesimus. The Apostle Paul had baptized Onesimus and he is now a valuable asset. Philemon must show love and gratitude for his runaway slave's newfound faith, forgive him, and receive him as a brother."