The answer is: His life

v19 - Paul mentions it, but is saying that he doesn't need to go into the details. Presumably Paul is talking about converting Philemon to a believer in Christ, rather than a literal saving of his life.

In Philemon, Paul’s excerpt brings a unique twist to the typical dynamics of letter-writing. Paul suggests that Philemon owes him his "life," referring not just to physical existence, but to his spiritual rebirth. This kind of living debt was quite common in Paul's day; often, followers would acknowledge their teachers or spiritual guides in such terms, making teachers and prophets like a second family.

What’s really fascinating is the social brilliance in this letter—it's a personal appeal that transcends just being a request for a runaway slave, Onesimus. Paul is effectively reminding Philemon that his transformation into a believer came through these candid efforts from Paul himself. Imagine receiving such an ultimatum, directly linking your own spiritual well-being to the actions you've taken with another person.

In addition, the letter to Philemon is the shortest of Paul's letters, with only 25 verses, and it showcases his masterful use of language and relationship-building. Did you know that many believe Philemon might have been Paul's friend? It's thought that the foundation of love and mutual respect they shared is what makes this short letter so potent.

This one plea ties beautifully into broader biblical themes of forgiveness and reconciliation, evoking echoes of stories like that of the Prodigal Son, where redemption weaves a common thread through personal narratives and larger community ideologies. So, Philemon's debt reminds us that spiritual journeys often wind back towards relationships that shape our growth!