One finds some of the most poignant and significant uses of the term “Father” for God in the work On Prayer (De oratione). Tertullian comments on the opening refrain of the pater noster by declaring: “Happy are they that acknowledge the Father!” Michael J. Brown has demonstrated that the pater noster is a distinctive invocation since it does not contain any sacred epithets (cognomina) that describe the God and Father of Jesus Christ. He suggests that the invocation, when heard by a typical Greco-Roman, would probably have evoked notions of a Roman household head (paterfamilias) or called to mind the ancient patron-client relationship as well as similar types of divine prayers incorporated in then contemporary Greco-Roman literature. Moreover, the prayer may have reminded some Roman citizens of the emperor, whom Romans considered father of their homeland (pater patriae). Tertullian himself probably viewed “Father” as a divine cognomen and metaphor. His exegesis of the dominical oration indicates as much since he linguistically parallels “Father” and “God,” indicating that he believes the former is an integral designation for the maximally excellent being: “Moreover, in saying ‘Father,’ we also call Him ‘God.’ That appellation is one both of filial duty and of power" (De oratione 2.10-11). Tertullian reasons that addressing God as pater obligates believers to obey or dutifully worship the omnipotent deity. By rendering “filial duty” (pietas) to the Father, one simultaneously honors the Son: “‘For I,’ says he, ‘and the Father are one' " (Ibid).
 The Lord’s Prayer through North African Eyes: A Window into Early Christianity (London and New York: T & T Clark International, 2004), 4.
 Cf. Matthew 10:25; 13:27, 52; 20:1, 11; 21:33; 24:43. One biblical Greek term for a household head commonly is oivkodespo,thj. See also the entry for ku,rio,j in BDAG.
 Brown, The Lord’s Prayer, 4; Eva Marie Lassen, “The Roman Family: Ideal and Metaphor,” in Halvor Moxnes (editor), Constructing Early Christian Families: Family as Social Reality and Metaphor (London and New York: Routledge, 1997), 110-112. See DI 5 for an example of the Emperor being called “parent” or Father. Cf. Tertullian’s Apologeticum 34.2.
 Ibid. Lord’s Prayer, 246.