The Epistle to Philemon is the shortest of all extant letters written by Paul. At first sight, and especially compared to the Epistle to the Romans, the Letters to the Corinthians and Galatians, it seems rather unremarkable. Here, Paul writes to mediate in a conflict between Philemon, a Christian in whose house a congregation meets, and his slave Onesimus, who too has now become a Christian. How Paul writes this letter, however, is what makes it a valuable lesson in Christian ethics, according to Peter Müller. Müller shows Paul´s completely new worldview, made possible through the fellowship with Jesus Christ and an influence on the fellowship of all believers. The central tenets of the letter – belief, love, fellowship – do not remain noncommittal, but rather become very concrete with respect to the relationsip of Philemon to his slave Onesimus. That Paul did not explicitly demand the freeing of Onesimus from slavery has often been rebuked in recent exegesis – something Müller rejects. In the world of ancient slavery and the existing legal terms, freeing a slave was not necessarily the best choice. And yet Paul demands of Philemon more than what was legally necessary: a new, changed relationship between slave and master which impacts everyday life. Müller shows that regulating the matter of a relationship among unequals was not simply a personal affair, but one that concerned the entire congregation, which is why the Epistle to Philemon is important even today.