Homoousios (Of One Essence)

The word is built from homos, "same," and ousia, "essence" — "of the same essence." To say the Son is homoousios with the Father is to say there is nothing the Father is that the Son is not: not similar divinity, not delegated divinity, but the selfsame Godhead. It is the dogmatic form of the Lord's own words — "I and my Father are one" (John 10:30) — and of the Gospel's opening line: "the Word was with God, and the Word was God" (John 1:1).

The occasion was Arius, who taught that the Son, however exalted, was a creature with a beginning. At the First Ecumenical Council at Nicaea in 325, the bishops discovered that every scriptural title they proposed — Word, Power, Image — the Arian party could quietly reinterpret of a creature. St. Athanasius, who attended the council as a young deacon and spent his life defending it, records the result: "the Council, as understanding this, suitably wrote 'one in essence,' that they might both defeat the perverseness of the heretics, and show that the Word was other than originated things." The unscriptural word was chosen precisely to protect the scriptural faith: it was the one word that could not be made to mean less than God.

The choice was audacious. The word does not occur in the Bible — its opponents pressed this hard — and it carried baggage: earlier generations had seen it misused, and many sober bishops feared it blurred the distinction of the Persons. So for two generations after Nicaea the Church convulsed. Rival councils multiplied, and a broad middle party proposed a compromise: homoiousios, "of similar essence" — one letter longer, one iota's difference. The Fathers who held the Nicene line saw that "similar" is a fatal word: what is only like God is not God, and a Christ who is almost God cannot join us to God. Salvation itself — our union with God — hangs on the Mediator being fully both.

Patient work by St. Athanasius and then the Cappadocian Fathers — who paired "one essence" with "three hypostases" so that unity no longer sounded like confusion of Persons — won over the hesitant. The Council of Constantinople in 381 reaffirmed the Nicene faith, and the Creed in the form it gave us has been the Church's confession ever since. The story is told at length in its own entry.

Every Orthodox Liturgy still confesses it: "Light of light; true God of true God; begotten, not made; of one essence with the Father; by Whom all things were made." The phrase "begotten, not made" is the word's plain-English shadow: what is begotten of the Father is what the Father is, as a son is what his father is; what is made is something else. And a century later the Council of Chalcedon (451) turned the same word toward us, confessing Christ consubstantial with the Father in His divinity and consubstantial with us in His humanity — the same essence as God, the same essence as you.

It is worth pausing at how strange and how wonderful this is: the faith of fishermen was safeguarded by a word from the schools, and a single syllable of Greek held the line for the Gospel. When the Church sings homoousios, she is saying that in Jesus Christ we do not meet a messenger, a lieutenant, or a lesser god — we meet God. "He that hath seen me hath seen the Father" (John 14:9). That is either the truth about Jesus or it is not; Nicaea staked everything on the fact that it is.