Philemon 1 - IVP New Testament Commentaries
Typically, Paul's last word to his readers reminds them of the availability of the grace of the Lord Jesus Christ: living within Christ's lordship will enable his disciples, especially Philemon, to respond to the apostle's advice (see commentary on Col 4:23). Martin adds that this prayer is a "liturgical grace that situates the letter in the house congregation at worship" (1991:145), reminding current readers that all Paul's writings are for nurturing the worshiping community.
Paul often adds the phrase with your spirit to his benediction (compare Gal 6:18; Phil 4:23; also 2 Tim 4:22). Not just a fuller but equivalent expression of "with you," this concluding phrase suggests the collaboration of Christ's Spirit, who mediates his grace, with Philemon's human spirit, which receives it and applies it to life (Wall 1979:128-44). Such an image lies at the very core of Paul's participatory Christology: God's salvation-creating grace transforms the believer who actively collaborates with Christ in the ongoing work of God.