When Paul tells Philemon to put Onesimus’ wrong on his “account” and that he would “repay” him (v.18), we know he “wronged” him financially. Slaves often robbed their masters to finance their escape, figuring they owed them for all their free labor. That sounds justified, but Paul calls it wrong, just as it is wrong when employees steal from their employer today because they’re not paid enough. If you’re guilty of that, stop (Eph.4:28). If you’re not, remember you might be someday (ICor.10:12).
If Onesimus did steal from his master, Paul says he owed him. When you steal from a man, you owe him, and in Bible days you had to pay it back with interest (Ex.22:1).
Paul was probably offering to pay Onesimus’ debt because he was broke and couldn’t pay it himself. He no doubt spent all his money on the 1200 mile trip from Colosse to Rome, so had to get a job at the prison where Paul was incarcerated.
If you couldn’t repay what you stole, then they imprisoned you (Mt.5:25) until you paid your debt, as prisoners pay their debt to society today, with the loss of your time and freedom.
Since Philemon is a book of illustrations, we know that this illustrates how when men sin against their master God, He considers it a “debt” that they owe Him (Mt.6:12-14). And it’s a debt they cannot pay, for sinners are spiritually broke.
They can’t pay their debt to God because they don’t have anything He wants. So they have to go to prison till they’ve paid “the last farthing” (Mt.5:25). You know that verse is about hell, because that’s how the Lord introduced it (v.22).
Men in hell must pay for their debt with more than their loss of time and freedom. They are “delivered to the tormentors” (Mt.18:34) until they’ve paid the last farthing of their debt. But sin against an eternal God demands an eternal punishment! Hell has to be eternal because men can never suffer enough to repay God for the enormity of their sin. Men say that’s not fair, but it’s fair because men don’t have to go to hell. The Lord took their torment on the cross. All they have to do to be saved from hell is to believe that.
This shows it is wrong to say, as some are saying, that the sins of unsaved men are forgiven. People go to hell “because” of their sins (Eph.5:6). Their only hope is to let Christ pay their debt, something else we see illustrated when Paul tells Philemon to put his slave’s debt on his account. That’s what the Lord did for us, put our sin on His account.
An “account” is a registry of debits and credits. Sin debits a man’s account with God, but he has no way to credit it, since God doesn’t accept good works as credit (Isa.64:6). But God counts faith for righteousness (Rom.4:5), faith in the fact that God made Christ to be sin for us so we might be made righteous (IICor.5:21).
Paul usually dictated his letters (cf.Rom.16:22), but made his offer to pay Onesimus’ debt with his own hand (Phile.1:19). He did this to give Philemon something he could take into court if need be and insist he pay the debt if he wanted to. That’s an illustration of how, when it comes to your sin debt, you have it in writing that Christ paid it in the writing of the Word of God.
Of course, Philemon would never make Paul pay his slave’s debt because he owed Paul his own self (Phile.1:19). He led him to the Lord and saved his eternal life, and perhaps saved him from a life of sin and degradation in this life. In bringing this up, Paul was implying he owed him a debt he couldn’t repay. That illustrates how you should feel about the Lord!
After all Paul had given to Philemon, he would never expect Paul to give him more by paying Onesimus’ debt. After all the Lord has given you eternally in the next life, do you really expect him to give you more in this life? By giving you health and wealth, and solving all of your problems?
Paul says you should live for Him who died for you “and rose again” (IICor.5:14,15). If a man saves your life, you feel like living for him, right? But if someone dies saving your life, you can’t live for him—but you can live for the Lord who died for you and rose again.