PERHAPS

"15 Perhaps the reason [Onesimus] was separated from you for a little while was that you might have him back for ever – 16 no longer as a slave, but better than a slave, as a dear brother. He is very dear to me but even dearer to you, both as a fellow man and as a brother in the Lord." Philemon 15-16

As he is writing to Philemon about receiving back his slave, Onesimus, the Apostle Paul is engaging in some conjecture about what God was doing behind the scenes in this whole scenario. 

Many people assume that Onesimus was a runaway slave, but there's nothing in the letter to confirm this as the backstory. It's just as likely that Philemon sent Onesimus to Paul for a short time in order to care for Paul's needs while he was imprisoned. 

Regardless of how Onesimus came in contact with Paul, he seems to have given his life to Christ during his time away from home and Paul now loves him like a son. 

Now, as he sends Onesimus back to his earthly master, Paul speculates that this round trip wasn't just about bringing aid and comfort to Paul.

Perhaps it was because the Lord knew that Paul would persuasively share the gospel with Onesimus, leading to a new birth. 

And THEN - even better - Onesimus would return to Philemon, not to help with household chores, but to function as a co-worker, a brother, in spreading the gospel.

I love the fact that Paul uses that word "perhaps". Even as Spirit-led as the Apostle is, he still only gets glimpses of what the Lord is up to as He guides His children this way and that.