Paul’s letter to Philemon is the gospel in street clothes; it’s the gospel on the ground and at work in real life. It’s for this reason we need this personal, yet powerful letter because isn’t this often where the challenge lies for us? We may be persuaded that the gospel is the power of God for salvation; we may be immovably convicted of its truthfulness; and we may even publicly confess it weekly as summarized in the Apostles’ Creed—but what difference does it make? What difference does the gospel make in my life, in the decisions I make, in the way I view my circumstances, in what I value and prize, in the way I relate to my brothers and sisters in the church? 
This challenge often arises from a truncated view of the gospel. We may think that it’s only about the forgiveness of my sins and my soul being made right with God. Now while that is vital to the gospel message, we need to recognize that the gospel is far more reaching and far more comprehensive than that. If at the center of the gospel is the resurrection of Jesus Christ from the dead by which he inaugurated a new creation of which I am already a part (see 2 Cor 5:17), then its practical implications will impact my whole life and all my relationships, especially in the church. (Re-read that last sentence because it’s going to be important later.)
Now returning to Paul’s letter, we need to say something about its background, if we’re to appreciate the gospel’s transforming power. Earlier during one of Paul’s missionary journeys, he encountered Philemon, a wealthy man traveling from his hometown, Colossae. Under Paul’s gospel preaching, Philemon was converted (so v. 19) and made a brother in the family of God. He returned to Colossae as a fellow gospel worker, even opening up his home for the church to meet in (v. 2).
But Philemon owned a difficult, troublesome and, therefore, useless (v. 11) slave, Onesimus. Eventually Onesimus took off with some of Philemon’s possessions (v. 18) and made his way to Rome—the place where, as the historian Tacitus wrote, “all things horrible and disgraceful find their way.” While in Rome, Onesimus encounters Paul, who is likely under house arrest (vv. 1, 9). And like his master before him, he too is converted under Paul’s gospel preaching and made a brother in the family of God and Paul’s spiritual son (v. 10). This runaway slave now becomes useful to Paul (v. 11) and very dear to his heart (v. 12), but there’s a problem…
Paul knows that Onesimus must return to his master, and he also knows that his crime is a capital offense since it threatened to undermine the Roman social order. So Paul sends Onesimus back to Philemon with this letter of appeal (v. 9) to receive him not as a slave, but as a brother. Now Philemon has every right to punish Onesimus, but Paul is requesting that he forego this right and instead receive him as a brother. How can he make this request?
At the heart of the letter, Paul reasons, “For this perhaps is why [Onesimus] was parted from you for a while, that you might have him back forever, no longer as a bondservant but more than a bondservant, as a beloved brother” (vv. 15–16).
Notice, the word “forever” makes a comparison between what is eternal and what is temporary. Paul isn’t contrasting what is good and what is evil, but what is eternal and what is temporary. This is huge for seeing the comprehensiveness of the gospel: Paul doesn’t see the gospel as only dealing with the problem of evil, he also sees it dealing with the problem of the temporary nature of this present creation. It’s characteristic of this present age (and the things that belong to this present age) to break down, wear out, rust, decay and eventually perish (see Matt 6:19–20)—this is a problem and the gospel is the solution.
Here’s where that sentence I asked you to re-read earlier comes into play. At the center of the gospel is Jesus’ resurrection by which he reversed the decaying effect of death and inaugurated a new creation. This new creation is marked by permanency, incorruptibility and eternality. And everyone whose eyes have been opened to the glory of the gospel and who have been united to the risen Christ by faith belongs to the new creation already.
Now it’s not just that the things of the old creation are temporary, but also the relationships, including the master/slave relationship. The temporary relationships of the old creation are transcended by the permanent and eternal relationships of the new creation, which we experience in Christ. Paul makes this point explicit in Gal 3:26–28, “…[I]n Christ Jesus you are all sons of God, through faith. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus” (see also Col 3:11). The relationships of the old creation that are marked by polarities (you are either one or the other) and characterized by an economic hierarchy (one side of the relationship is valued higher in the economy of the present age) do not continue into the new creation in Christ. In Christ the people of God relate as the one, unified family of God.
So in the case of Philemon and Onesimus, in Christ they ultimately relate to one another as brothers of equal standing, not as master and slave. Likewise, in Christ, we relate to one another as the one family of God, as brothers and sisters, fellow workers, co-heirs, equals. This principle stands behind Paul’s own willingness in this letter to forego exercising his apostolic authority. You probably noticed that he doesn’t explicitly mention he’s an apostle (which contrasts with his letter to the Galatians). This principle also enables Paul to elevate the position of others to equal standing with himself whether they are office bearers or laypeople—everyone is either a brother, sister, fellow worker, or fellow soldier. The gospel, then, empowers us to forego our right to what is temporary (even if it is good and lawful), so that we might relate to one another on the basis of what is eternal and so gain what is eternal. The same ethic is at work in 1 Cor 7 (with respect to marriage), 1 Cor 8 (with respect to food offered to idols), and 1 Cor 9 (with respect to receiving wages).
Think about the massive practical impact this ethic has on our life together as a church. We can avoid conflict over matters that fade in their significance in the light of eternity. We can downplay our own importance and elevate the positions of others. We can rejoice in the success of a brother or the gifts of a sister, instead of growing jealous. We can overlook an offense or bear a sibling’s burden, knowing that we’re in this together as the one family of God forever.
Have you ever thought that the relationships you have with your brothers and sisters in church belong to the new creation and will therefore continue into eternity? This should encourage us to highly value and prize these relationships today as well as to foster and develop them in ever-deepening fellowship with one another. Paul, after reminding the Ephesians that they have put off the old self and put on the new, instructs them, saying, “Let each one of you speak the truth with his neighbor, for we are members one of another” (Eph. 4:25). When this ethic is operative in the church then we “grow up in every way into him who is the head, into Christ” (4:15).
We asked earlier if the gospel makes a difference. I hope we can see now that nothing makes a bigger difference because nothing else has the power to lift our lives out of the temporary and fleeting to engage in what is eternal and forever.
 See http://www.sermonaudio.com/sermoninfo.asp?SID=221121317486