Anomoeanism: Radical Arianism

The Story

To understand anomoeanism, you first need to understand the alphabet soup of fourth-century Trinitarian theology. After Nicaea (325) declared the Son homoousios (“of the same substance”) with the Father, a spectrum of alternative positions emerged. Moderate Arians said the Son was homoiousios (“of similar substance”). Homoians like Acacius of Caesarea said the Son was simply “like” (homoios) the Father, and wanted to avoid the word “substance” altogether. And then, at the far end of the spectrum, stood the anomoeans — from the Greek anomoios, meaning “unlike.” The Son, they argued, was not merely different from the Father in degree. He was different in kind. The Son’s essence was utterly unlike the Father’s essence. No hedging, no qualifications, no diplomatic fudging.

The intellectual architect of anomoeanism was Aetius (c. 313-367), a remarkable and widely disliked figure. Born in Antioch, Aetius worked as a goldsmith, a tinker, and possibly a vineyard laborer before turning to philosophy and theology. He was trained in Aristotelian logic and brought a logician’s ruthless precision to theology. His key work, the Syntagmation (a series of logical syllogisms), argued that “unbegottenness” (agennesia) was the defining attribute of the Father’s essence. Since the Son is “begotten,” the Son cannot share the Father’s essence. Different defining attribute, different essence. Full stop. It was a tight, elegant argument, and it horrified almost everyone.

Aetius’s most capable student was Eunomius of Cyzicus (c. 335-394), who became the public face of the movement. Eunomius was a better writer and a more politically astute operator than his teacher. He served briefly as bishop of Cyzicus before being deposed, and his Apology became the definitive anomoean text. Eunomius pushed the logic further: since the Son’s essence is unlike the Father’s, and since the Holy Spirit is produced by the Son, the Spirit is unlike both — making the three “persons” of the Trinity three fundamentally different beings, hierarchically ranked.

The anomoeans found their political moment at the Council of Sirmium in 357, where a creed was promulgated (later dubbed the “Blasphemy of Sirmium” by its opponents) that declared the Father “greater” than the Son and forbade the use of ousia (“substance”) language altogether. While the Blasphemy of Sirmium was not strictly anomoean — it was backed by homoian politicians like Ursacius and Valens — it created the theological space in which anomoeanism flourished. The backlash was enormous. Even moderate semi-Arians were appalled, and the Blasphemy of Sirmium is often credited with driving the middle parties back toward the Nicene camp. Basil of Caesarea, Gregory of Nazianzus, and Gregory of Nyssa — the Cappadocian Fathers — wrote devastating refutations of Eunomius that became classics of Trinitarian theology. The First Council of Constantinople (381) reaffirmed the Nicene Creed and definitively closed the door on all forms of subordinationism, anomoeanism included.

What the Council Actually Said

The “Blasphemy of Sirmium” (357), which anomoeans used as cover, stated:

“There is no doubt that the Father is greater in honor, in dignity, in splendor, in majesty, and in the very name of Father… And no one is ignorant that it is catholic doctrine that there are two persons of the Father and the Son, and that the Father is greater.”

The First Council of Constantinople (381) responded by expanding the Nicene Creed to include the full divinity of the Holy Spirit:

“We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father, who with the Father and the Son together is worshiped and glorified.”

Basil of Caesarea wrote against Eunomius:

“He says that the essence of God is unbegottenness itself… as though we were bound to have not the fact but the name for the whole of our theology.”

Why You Might Accidentally Believe This

You probably will not stumble into full anomoeanism by accident — it is too extreme for most people’s instincts. But softer versions of its logic are surprisingly common. Whenever someone thinks of the Father as “the real God” and the Son as a lesser, created being who mediates between God and humanity, they are on the anomoean trajectory. Jehovah’s Witnesses, who teach that the Son is a created being (Michael the archangel in pre-incarnate form), hold a position that Aetius would have recognized as a close cousin of his own.

More subtly, anyone who ranks the persons of the Trinity hierarchically — “the Father is in charge, the Son obeys, the Spirit executes” — is flirting with the subordinationism that anomoeanism represents in its most radical form. The “eternal functional subordination” debate in recent evangelical theology touches on exactly this nerve.

The Strongest Case For This View

Aetius and Eunomius were rigorous logicians, and their core syllogism has real force. If “unbegottenness” defines the Father, and “begottenness” defines the Son, then they have different defining properties. Different defining properties mean different essences. This follows standard Aristotelian logic. The Nicene party’s response — that begottenness is a relational property, not an essential one — required a philosophical move that Aetius regarded as ad hoc.

There is also a biblical case. The New Testament repeatedly subordinates the Son to the Father. “The Father is greater than I” (John 14:28). “The Son can do nothing on his own” (John 5:19). “My God, my God, why have you forsaken me?” (Mark 15:34). 1 Corinthians 15:28 says that in the end, “the Son himself will be subjected to him who put all things in subjection under him, that God may be all in all.” If you read these texts without the Nicene framework, a subordinationist reading is natural, and anomoeanism is simply subordinationism taken to its logical conclusion.

The Strongest Case Against

The Cappadocian Fathers dismantled anomoeanism on both philosophical and theological grounds. Gregory of Nyssa argued that “unbegottenness” is not a definition of the Father’s essence but a description of his mode of origination. The Father is unbegotten, the Son is begotten, and the Spirit proceeds — but these describe how they relate to each other, not what they are. What they are is the same divine essence. The analogy (imperfect, like all Trinitarian analogies) is that Peter, James, and John all share human nature, even though they are distinct persons. Begottenness no more changes the Son’s essence than being born in Galilee changes Peter’s humanity.

Theologically, anomoeanism empties Christianity of its distinctive claim. If the Son is a creature — however exalted — then the incarnation is not God entering the world but a secondary being entering the world. Worship of Christ becomes idolatry (worship of a creature), and salvation loses its engine. Athanasius had made this argument against Arius decades earlier, and it applied with even greater force to the anomoeans, who pushed the Son further from the Father than Arius ever had.

The “Blasphemy of Sirmium” also demonstrated the political danger: a Christianity that subordinates the Son licenses authoritarian hierarchies in which the emperor (aligned with the “greater” Father) can dictate to the church (aligned with the “lesser” Son). The Nicene insistence on equality within the Trinity was, among other things, a check on imperial theology.

What the New Testament Actually Says

The New Testament contains both high-Christology texts (John 1:1, “the Word was God”; John 10:30, “I and the Father are one”; Philippians 2:6, “in the form of God”) and subordinationist-sounding texts (John 14:28, Mark 13:32, 1 Corinthians 15:28). The anomoeans read the subordinationist texts as literal descriptions of ontological reality and the high-Christology texts as honorific language — the way a king might call his viceroy “my equal” without meaning it literally.

The Nicene party read them the other way around: the high-Christology texts describe what the Son is, and the subordinationist texts describe the Son’s voluntary self-emptying in the incarnation. Both readings are possible. What Nicaea, Constantinople, and the Cappadocian Fathers established was a hermeneutical framework in which the high-Christology texts set the baseline and the subordinationist texts are read within that framework. Whether that framework is the best reading of the New Testament or a fourth-century overlay remains a matter of theological commitment.

Further Reading

• What Is Arianism, Simply Explained? — The broader Arian movement from which anomoeanism emerged
• Homoianism — The moderate anti-Nicene position that anomoeanism radicalized
• When “Orthodox” Was the Heretical Position — How the Nicene party was a minority for much of the fourth century
• The Council of Rimini — The moment when the anti-Nicene coalition seemed to win