The Most Important Word in the Whole of History

On every Solemnity (that includes Sundays) the Catholic Church professes, within her Eucharistic Liturgy, the faith of the Nicene (Constantinopolitan) Creed. The Fathers of the Council of Nicaea in 325 AD formulated this creed in response to the Arian heresy.

For centuries the Fathers of the Church attempted to conceive and articulate how God could be One and the Son of God also be truly God – faith demanded that both be true. Various efforts were made. The most advanced, as exemplified in Origen (d. 253), was that of seeing God the Father as the one who possessed the fullness of the Godhead with the Son (and Holy Spirit) emanating out from him.

Notwithstanding Origen’s great achievement, the obvious problem with this approach is that while the Son (and Holy Spirit) may be divine in that they share in the Father’s eternal divinity, they are not as fully divine as the Father is divine. They are ontologically subordinate to the Father.

In the light of many flawed or failed attempts, Arius (256-336 AD), a priest of Alexandria, concluded that it is impossible for God to be One and the Son of God be God. God alone, for Arius, is without beginning, unbegotten, and eternal. Thus, in order to preserve the truth that God is One, Arius concluded that the Son must be a creature, though the highest of all God’s creatures, and so the most divine-like. While the Son is “the only begotten of the Father,” he is created. Therefore, as created, Arius famously concluded that there was a time when the Son was not.

Arius marshaled a whole array of scripture passages in support of his conclusion, for example: “The Lord created me at the beginning of his work, the first of his acts of long ago” (Proverbs 8:22); “He is the image of the invisible God, the firstborn of all creation; for in him all things in heaven and on earth were created” (Colossians 1:15-16); and “The Father is greater than I” (John 14:28). Moreover, those passages in the New Testament that attribute divinity to the Son, such as John’s Prologue, do so, according to Arius, only in an honorific fashion.

Arius’s denial that the Son was truly God caused such an uproar within the Church that Emperor Constantine I summoned a Council in 325 that met in the city of Nicaea. The question for most of the bishops present at the Council was not whether the Son was truly God, for that was the faith of the Church from its foundation. Rather, the conundrum before them was how to conceive correctly and to articulate clearly the oneness of God while simultaneously professing that the Son is also truly God.

The first attempt, as was done in the past, was to employ Scripture passages that declared the full divinity of the Son – such as the Son being the only begotten of the Father (e.g., John 1:15). St. Athanasius, who was present at the Council as a deacon, tells us, however, that when this “creed” was proposed, the Arians in attendance “whispered and winked” at one another. Why such whispering and winking? Having already concluded that the Son was a creature, they could interpret all Scripture passages from within that template. Yes, the Son is the only-begotten of the Father, but he is only-begotten as the first creature made by the Father. This failed attempt forced the “orthodox” bishops to look for a new strategy for refuting Arius and professing the true faith. The Council of Nicaea ended up doing something that was never done before.


It seized upon a non-Biblical word in order to assure the proper interpretation of Scripture, and therefore the reading of Scripture within the apostolic tradition. The Creed professes belief in the Lord Jesus Christ who is the eternal only-begotten Son of God. He is “God from God, Light from Light, true God from true God.” It then makes a significant distinction, one that was never clearly made before. The Son is “begotten, not made.” That which is “made” is of a different nature than the maker. Thus, God made/created all that is. However, that which is begotten is always of the same nature as the begetter. Thus, the Son is begotten of the Father, and so he is “consubstantial” (homoousion) with – that is, of the same nature as – the Father.

The word homoousion is the non-biblical word that assures the proper reading of Scripture. The title “Son of God” must now be interpreted to mean that, as the Father’s Son, the Son is God as the Father is God, for they possess the same divine nature. Moreover, no longer is the Son conceived as emanating out from the Father and so subordinated to the Father. Rather, the one nature of God, what the One God is, is the Father eternally begetting his divine Son. The Father’s begetting of his Son is constitutive of their one divine nature.

Thus, the Church, in accord with the New Testament proclamation, had now conceived properly and articulated clearly how God can be One and the Son be God. The Council of Nicaea did what Arius thought impossible to do. The Homoousion doctrine both distinguishes the Father and the Son, as well as affirms their oneness, for the Son is of one and the same nature (homoousion) as the Father.

The Homoousion doctrine, then, not only protects and advances the proper reading of Scripture, but it also protects and professes a proper and correct understanding of the mystery of the Trinity. (Later, at the First Council of Constantinople in 381, the full divinity of the Holy Spirit will be professed, with the implication that the Holy Spirit is also homoousion with the Father and the Son.) Moreover, homoousion assures that the same Son who is consubstantial with the Father is the same Son who “for us men and for our salvation came down from heaven, and by the Holy Spirit was incarnate of the Virgin Mary, and became man.” Homoousion is thereby the guardian of the Incarnation – that Jesus is truly the Son of God incarnate.

Likewise, homoousion guarantees our salvation, for the same Son, He who is one with the Father, “for our sake was crucified under Pontius Pilate, suffered death and was buried, and rose again on the third day.” We now await his return in glory when his kingdom will be without end. Similarly, homoousion confirms the reality of the sacraments. It is the incarnate fully divine Son who baptizes us in the Holy Spirit, and it is the risen body and risen blood of this incarnate divine Son, who is one in being with the Father, whom we receive in the Eucharist.

Simply put, homoousion is the most important word in the whole of human history – past, present, and future! Without it, the whole of the Gospel, the whole of the one, holy, catholic, and apostolic faith would be rendered void. Homoousion, then, in all its splendor, beauty, and TRUTH, is the word upon which our faith and the world’s salvation is founded – now and forever.


*Image: The Heavenly Glory [detail: central section] by Pierre Mignard, 1663 [Val-de-Grâce, Paris]. This depiction of the Blessed Trinity is the centerpiece of Mignard’s fresco for the church’s dome, commissioned by Anne of Austria, wife of King Louis XIII of France. Father, Son, and Holy Spirit are surrounded by the faithful:

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Thomas G. Weinandy, OFM, a prolific writer and one of the most prominent living theologians, is a former member of the Vatican’s International Theological Commission. His newest book is the third volume of Jesus Becoming Jesus: A Theological Interpretation of the Gospel of John: The Book of Glory and the Passion and Resurrection Narratives.