This chapter explores the reception of classical ethical philosophy in the fourth-century Cappadocian Father, Gregory of Nazianzus, by focusing on the first of his five Theological Orations (Or. 27). An Athenian-trained rhetorician who became the most widely studied and imitated author in Byzantium, Gregory weaves together various strands from ancient ethical discourse in order to set out the moral and cultural prerequisites for performing theology. Gregory’s construction of the ideal theologian reflects late-antique discussions about the proper exegesis of texts, the moral character expected of teachers and students, and the policing of discourse. Finally, Gregory distinguishes the appropriate performance of theology from theology performed simpliciter through a set of qualifications that reflect a recognisably Aristotelian framework, one that can be traced back to the Nicomachean Ethics.