This book provides new research on family and sibling relations in the Greco-Roman and Jewish context and discusses the relevant texts on siblingship in the seven authentic Pauline letters. A main thesis is that the sibling terminology is both central and charged with meaning for Paul. When he speaks of the Christians as siblings, he employs contemporary notions of what sibling and family relations should be about: displaying emotional closeness, show love, be tolerant and forgiving, defend family honour, and strive for familial harmony. In various contexts Paul utilises these ideals rhetorically in order to influence the attitudes and behaviour of the Christians, both internally and in relation to outsiders. Since siblingship and family relations were so important in antiquity, Paul's use of this kind of language was significant and powerful. The book is an in-depth study of Christian relations according to Paul. Its conclusions have important consequences for our understanding of ethics and ecclesiology not only in Paul, but also in the New Testament in general. The book combines metaphor theory, socio-historical perspectives and exegesis of Pauline texts in ways that produce new insights both intoPaul's thinking and into several passages of his letters.