Pope Leo Asks: What Has Arius to Do With Jesus?

National Catholic Register, 4 December 2025

Marking the 1,700th anniversary of the Council of Nicaea, the Pope contrasts orthodox faith with the claims of Arius and outlines how the Church must address the ‘new Arianism’ in today’s culture.

On his visit to Turkey to commemorate the 1,700th anniversary of the Council of Nicaea, Pope Leo XIV took up two themes dear to his predecessors, Pope Benedict XVI and Pope St. John Paul II. He offered a difference in emphasis from the former, and an echo of the latter in the context of Arianism, the heresy that Nicaea was called to confront.

Arianism — named after its most famous proponent, Arius, a priest and theologian from Alexandria — held that Jesus was not divine to the same degree as the Father was divine. He was exalted and anointed to be sure, but not equal in divinity to the Father. Thus, the Council of Nicaea in 325 took up a fundamental question for the Christian faith: Who is Jesus Christ?

Nicaea condemned Arianism and gave us the formula repeated on Sundays at the Holy Mass: God from God, Light from Light, True God from True God. The Nicene Creed employed a term from Greek philosophy, rendered into English as “consubstantial.” “Substance” is a term meaning the nature of a thing, its being. Thus, to say that Jesus is “consubstantial” with the Father is to affirm that they have the same nature, same being. The Father and the Son, incarnate in Jesus Christ, are both equally God.

The decision of Nicaea to reach outside the sacred Scriptures to define the relationship between the Father and Jesus, to employ the language and concepts of (pagan) Greek philosophy, was not without controversy. Does divine Revelation need nonbiblical language to express itself properly? Should the Church incorporate philosophical concepts that are not themselves rooted in divine Revelation?

The famous and enduring question puts it directly: What has Athens to do with Jerusalem?

In his long career, Joseph Ratzinger (Benedict XVI) returned to that question often. In his notable Regensburg Address, delivered just a few months before his own visit to Turkey in 2006, Benedict argued that it was part of God’s providential plan that Revelation would employ the concepts of Greek philosophy:

“Modifying the first verse of the Book of Genesis, the first verse of the whole Bible, John began the prologue of his Gospel with the words: “In the beginning was the λόγος” (logos). … Logos means both reason and word — a reason which is creative and capable of self-communication, precisely as reason. John thus spoke the final word on the biblical concept of God, and in this word all the often toilsome and tortuous threads of biblical faith find their culmination and synthesis. In the beginning was the logos, and the logos is God, says the Evangelist.” 

The encounter between the biblical message and Greek thought did not happen by chance. St. Paul’s vision — the Macedonian man pleading in a dream, “Come over to Macedonia and help us!” (Acts 16:6-10) — can be interpreted as a “distillation” of the intrinsic necessity of a rapprochement between biblical faith and Greek inquiry.

Benedict speaks boldly of the “intrinsic necessity” of biblical faith being expressed in the concepts of ancient Greek philosophy. A term for this is “Hellenism” or “Hellenization” — Greece’s official name is the “Hellenic Republic.”

Should the Christian faith be Hellenized? Is that not to narrow God’s self-revelation into a particular language and culture? The question is complex, and Pope Leo took it up, albeit briefly, in a letter regarding the 1,700th anniversary, released just a few days before he departed Rome. The apostolic letter was entitled In Unitate Fidei (In the Unity of Faith).

“The Fathers confessed that Jesus is the Son of God inasmuch as he is of the substance (ousia) of the Father ... “begotten, not made, consubstantial (homooúsios) with the Father.” This definition was a radical rejection of Arius’ thesis.” 

In order to express the truth of the faith, the Nicene Council adopted two words — “substance” (ousia) and “consubstantial” (homooúsios) — which are not found in Scripture. The Council’s intention in doing so was not to replace biblical statements with Greek philosophy. On the contrary, it used these terms precisely to affirm biblical faith with clarity and to distinguish it from Arius’ error, which was deeply influenced by Hellenism. For this reason, the accusation of Hellenization should be directed at the false doctrine of Arius and his followers, not the Fathers of Nicaea.

There is no strict disagreement between Benedict and Leo, but there is certainly a divergence in emphasis. Benedict celebrates the Hellenization of Nicaea, rooting that very Hellenization in the Scriptures themselves, while Leo concedes that the Greek language of Nicaea was a necessary counter to the corrupting Hellenism of Arius and the heterodox party. He speaks of the “accusation of Hellenization” as something to be refuted. That divergence in emphasis will bear watching as the pontificate of Leo XIV develops.

Continue reading at the National Catholic Register.