Philemon 6 (NIV)
6 I pray that your partnership with us in the faith may be effective in deepening your understanding of every good thing we share for the sake of Christ.
I don’t think that the apostle Paul was simply putting the pressure on Philemon. Guilting someone into doing what is right is not the Gospel way. Paul understood the power of the Gospel and he knew the transformation that occurred in one who trusted in Christ—he makes that clear in 2 Corinthians 5:17, new creation! Everywhere we turn in Paul, he grounds his imperatives (commands) in the indicatives (descriptions). He only commands holiness because he first describes Christians as saints (holy ones). He only commands love because he describes Christians as those in whom the Holy Spirit has poured out the love of God.
When Paul is writing to Philemon about his runaway slave, Onesimus, he starts with reminding Philemon of the Gospel and its implications. He speaks of Philemon’s love and faith (v. 5) and notes that many believers have already been refreshed by him (v. 7). This language proves to be important, as Paul will end the body of this letter with an appeal to Philemon to “refresh” his heart, just as earlier he noted Philemon had refreshed others.
In verse 6, Paul lays out this Gospel reality: living faith is effective. Doug Moo paraphrases this verse this way: “Philemon, I am praying that the mutual participation that arises from your faith in Christ might become effective in leading you to understand and put into practice all the good that God wills for us and that is found in our community; and do all this for the sake of Christ.”
Faith leads to “mutual participation” or “partnership”—the Greek word there is koinonia. One who has genuine faith automatically has an organic relationship with all others who share such faith. Those who are in Christ are in Christ with all others who are in Christ. This koinonia implies a change in our relationships and requires that we view all our relationships through the lens of the Gospel.
Onesimus is now a brother to Philemon and shares not only in new life but in eternal life. Onesimus is no foreigner any longer, but a sibling, adopted by the same heavenly Father. This new relationship binds Philemon, it compels him (cf. 2 Corinthians 5:14-16). Paul knows that the moment Philemon hears the report that Onesimus has been rescued from his sins and transferred from the kingdom of darkness to the kingdom of light (cf. Colossians 1:13), his heart will be moved. It can’t help but be moved. The same Spirit in Philemon is in Onesimus.
There is something very significant about the partnership that we have as Christians. This fellowship, this mutual participation in the Gospel is what caused the earliest Christians to sell all they had so that no one among them would have need (Acts 4:32-37); they were giving for people they most likely did not know well at all. It is also what caused Gentile Christians to give generously to their Jewish brothers and sisters who were suffering (2 Corinthians 8-9); people they had never met and, more than likely, would never meet (at least this side of eternity). Faith in Christ binds us with all others who have faith in Christ. Period.
This partnership has multiple levels of application. It must control the way we live with those in the local body, sharing in profound mutuality (1 Corinthians 12), knowing that we need others and they need us. And their need is our responsibility. It must challenge us to be finding ways to support the persecuted church around the world and so prove that our love is genuine (2 Corinthians 8:8). It must lead us not only to do the unexpected in our relationships, but to do even more than that. To give and serve like the Macedonian Christians who gave “beyond their means, of their own accord, begging us earnestly for the favor of taking part in the relief of the saints—and this, not as we expected, but they gave themselves first to the Lord and then by the will of God to us (2 Corinthians 8:3-5).”
We cannot claim faith without considering the implications of that faith. The implications are vast because they are glorious. They are glorious because their source, God Himself, is glorious.
“The grace of the Lord Jesus Christ be with your spirit (Philemon 25).”
 Moo, D. J. (2008). The letters to the Colossians and to Philemon (p. 394). Grand Rapids, MI: William B. Eerdmans Pub. Co.