In his letters, the apostle Paul commonly refers to his fellow believers as "adelfoi", as his "brothers and sisters". Here, Reidar Aasgaard offers the first in-depth, and by far the most profound, analysis of this sibling vocabulary in the Pauline epistles. Aasgaard researches family and sibling relationships in the Graeco-Roman and Jewish context and discusses the relevant texts on siblingship in Paul's letters. He argues that sibling terminology is both central and charged with meaning for Paul. When the apostle speaks of the Christians as siblings, he employs contemporary notions of what sibling and family relations should be about: emotional closeness, love, tolerance and forgiveness, defense of family honor, and familial harmony. Paul utilizes these ideals rhetorically in various contexts in order to influence the attitudes and behavior of the Christians, both internally and in relation to outsiders.