Homoiousios
Definition
Homoiousios is the Greek term, “of similar substance,” used by a fourth-century “middle party” at the Council of Nicaea who held that the Son was not a creature but denied that he was, strictly speaking, the very same essence as the Father.1 It stands opposite homoousios, “of the same substance,” the term the council actually adopted to describe Jesus’s relationship to God the Father.1
Historical Development
Archibald Alexander Hodge counts three parties at Nicaea in AD 325, not two. The orthodox party insisted that the Son was “of the same identical substance with the Father,” applying the term homoousion to teach that Father and Son share one numerical essence. The Arians held the opposite: the Son was heteroousion, “of different or generically unlike essence from the Father,” a creature more like God than any other creature but not God himself. Between them stood a “middle party, styled Semiarians, who confessed that the Son was not a creature, but denied that he was in the same sense God as the Father is.” On their account the Father freely caused a divine person of like nature to proceed from himself from eternity, “truly similar, and derived from the Father… generically though not numerically one.”1 Their term for this, homoiousion, differs from homoousion by a single Greek letter, iota, but named a different relationship: likeness rather than identity of essence.
John Gill treated homoiousios as the Arians’ own countermove rather than a neutral synonym. Introducing his Body of Doctrinal Divinity, Gill wrote that “the Athanasians had as good a right to use the word [homoousios] as the Arians [homoiousios], and thereby explain their sense and defend their doctrine concerning the person of Christ, and his equality with God, against the latter, who introduced a phrase subversive of it.”2 Gill’s point answered a standing objection to homoousios: that Scripture never uses it. Hilary of Poitiers had already made the same reply on the orthodox side, arguing that anyone who rejects homoousios as unscriptural has the identical problem with homoiousios, since neither word appears in the Bible either.2
Homoiousios also came under attack from the opposite direction. Eunomius, the fourth-century Anomoean whose own position pressed Arius’s logic further than most Arians would go, argued in his Apology against applying either homoousios or homoiousios to the Son, on the ground that “the one implies a generation and division of the essence and the other an equality” between Father and Son that his system could not allow; he pressed the same objection against calling the Holy Spirit homoiousios with the Father.3 Nicenes judged the term an inadequate halfway measure and Eunomius judged it already too strong a statement of likeness, and it settled into neither camp’s vocabulary for the Trinity.
Confessional Witness
The Reformed confessions inherited the Nicene settlement, not the Semiarian middle term. The 1689 Second London Baptist Confession states that Father, Son, and Holy Spirit are “of one substance, power, and eternity, each having the whole divine essence, yet the essence undivided,”4 the homoousion position described above.
Related Doctrines
References
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Archibald Alexander Hodge, Outlines of Theology (New York: Robert Carter and Brothers, 1879), chap. 9, “The Holy Trinity,” 166-67. ↩ ↩2 ↩3
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Steven Tshombe Godet, “Gill’s Doctrine of the Trinity: Its Importance and Definitions,” in “The Trinitarian Theology of John Gill (1697-1771): Context, Sources, and Controversy” (PhD diss., The Southern Baptist Theological Seminary, 2015), 198-99. ↩ ↩2
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Keith Wesley Goad, “Gregory the Grammatical Theologian,” in “Trinitarian Grammars: A Comparison of Gregory of Nazianzus and Some Contemporary Models” (PhD diss., The Southern Baptist Theological Seminary, 2010), 48, 54. ↩
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The Second London Baptist Confession of Faith (1689), chap. 2, “Of God, and of the Holy Trinity,” para. 3. ↩