Commemorating Nicaea, an opportunity to “foster reconciliation and strengthen the search for unity among the various Christian traditions”.

This year marks 1,700 years since one of the most significant councils in Church history: the Council of Nicaea. This council affirmed the foundational Christian tenet that Christ is both true God and true man. Its commemoration represents, for Christians, the Church, and the ecumenical movement alike, a profound opportunity to reflect on the doctrinal and structural origins of Christianity.

From April 2nd to 5th, an academic congress was held in Rome to commemorate seventeen centuries since the Council of Nicaea. The event was hosted by the Pontifical Patristic Institute Augustinianum and the Pontifical University of Saint Thomas Aquinas (Angelicum), with the collaboration of several other institutions including the Institute of Eastern Christian Studies in Toronto, the Australian Catholic University, Domus Australia, and the A.G. Leventis Foundation. Father Juan Antonio Cabrera Montero, OSA, president of the Augustinianum, inaugurated the event, which gathered dozens of scholars from around the world.

Notable participants included former Archbishop of Canterbury Rowan Williams, Christoph Markschies, Lewis Ayres, Emanuela Prinzivalli, Samuel Fernández, Chiara Curzel, and Angelo Segneri—some of whom are faculty members at the hosting institute.

Throughout the sessions, scholars revisited the teachings of the Church Fathers, from Irenaeus of Lyon and Clement of Alexandria to Jerome and Gregory the Great—and, naturally, Augustine of Hippo. The Council of Nicaea helped shape Christianity’s understanding of the interplay between the human and the divine, embedding a humanistic worldview grounded in trust and optimism.

To shed further light on this congress, we spoke with Father Felipe Suárez Izquierdo, OSA, professor of Fundamental Patrology at the Augustinianum.

When was the decision made to organize this Congress?

Planning for the congress, titled “Nicaea 2025: Event, Context, and Reception”, began three years ago to mark the 1,700th anniversary of the Council of Nicaea in 325 AD. It is jointly organized by the Pontifical Patristic Institute Augustinianum and the Pontifical University of Saint Thomas Aquinas (Angelicum).

What significance does the commemoration of Nicaea hold for Christians, the Church, and ecumenism?

The remembrance of the Council of Nicaea (325) constitutes a pivotal moment of reflection for Christians, the Church, and the ecumenical movement. The council was a landmark in Church history, establishing for the first time an official and unified formulation of the Christian faith—the Nicene Creed—aimed at addressing the doctrinal tensions of the era, particularly concerning the identity of Christ.

For Christians broadly, revisiting Nicaea is a return to a foundational period when essential elements of shared faith were defined, offering a common point of reference that transcends current denominational divides. For the Church, it is both an affirmation of the dogmatic unity achieved and a sober acknowledgment of the complex entanglement between political power and ecclesial structure, a dynamic that has profoundly influenced the Church’s subsequent history.

From an ecumenical perspective, the commemoration of Nicaea holds both symbolic and practical value. Numerous Christian denominations—Catholic, Orthodox, and many Protestant traditions—regard the Nicene Creed as a shared theological heritage. This makes the council a historical site of convergence, potentially fostering dialogue, reconciliation, and the pursuit of unity among diverse Christian communities—not through imposed uniformity, but through the recovery of a shared memory.

In essence, commemorating Nicaea is not merely an act of historical remembrance, it is also an invitation to critically re-examine the foundations of the Christian faith, to understand the processes that shaped its institutional development, and to promote spaces of communion within diversity.

Simplified narratives about Nicaea—such as Constantine’s excessive influence—are often repeated. How would you respond to these portrayals? Is there a need to clarify the Council’s historical context?

It is essential to ask: from what perspective do we wish to approach Constantine? Should it be theological, historical, devotional—given that he is venerated as a saint in the Eastern Church—or from a critical reading of the sources? Without clarity on this point, interpretations of Constantine risk becoming distorted.

There exists an extensive body of literature, both ancient and contemporary, on Constantine’s role in the Council of Nicaea. Already in the Patristic period, he was the subject of significant writing, underscoring his central role in religious affairs. Regardless of whether one views him in a favorable or critical light, it is evident that before, during, and after his reign, the interweaving of political and religious spheres was inescapable. The modern concept of secularism simply did not exist. In the pagan worldview, civic identity and religious affiliation were inseparable, a citizen could simultaneously serve as a soldier and as a priest in his household. Communities that deviated from this socio-religious unity were regarded with suspicion, which partly explains the early persecutions of Christians.

While Constantine’s imperial protection significantly bolstered the Church’s institutional development, it also brought constraints. His involvement made Christianity a matter of political interest and management, introducing partisanship into theological debates and complicating their resolution. This politicization played a role in prolonging major doctrinal controversies, as evidenced in both the Arian crisis—which spanned the periods before, during, and after Nicaea—and the Donatist controversy, which unfolded during Constantine’s time in the West.

Who were the key figures at Nicaea and in its aftermath?

Among the most influential figures of the Council of Nicaea (325) was Emperor Constantine himself, whose initiative and political backing were instrumental in convening the council. On the theological front, historian Adolf von Harnack identified five Trinitarian positions represented at the council.

Arius, a presbyter of Alexandria, was the principal proponent of the view that denied the full divinity of the Son. Eusebius of Caesarea occupied an intermediate position between Arius and Alexander of Alexandria and played a vital role not only as a theologian but also as a chronicler—his works preserve much of what we know about the council and Constantine. Alexander of Alexandria, along with his young deacon Athanasius, staunchly defended the consubstantiality of the Son with the Father, a doctrine that ultimately prevailed in the Nicene Creed. Other significant participants included Eustathius of Antioch, who espoused a moderate form of monarchianism, and Marcellus of Ancyra, a proponent of dynamic monarchianism—both perspectives concerned with safeguarding divine unity against subordinationalist interpretations.

In the post-conciliar period, Athanasius emerged as a pivotal figure in the defense of Nicene orthodoxy, enduring multiple exiles and theological battles. His steadfastness was crucial to the eventual consolidation of Trinitarian doctrine. Later, the Cappadocian Fathers—Basil of Caesarea, Gregory of Nazianzus, and Gregory of Nyssa—made decisive contributions by refining and systematizing Trinitarian theology, laying the groundwork for its eventual ratification in subsequent councils.

How does Augustinian spirituality relate to Nicaea? And what about Augustine himself?

To speak of Nicaea during Augustine’s time is to refer above all to the “Nicene faith” as a doctrinal framework already integrated into Christian theological thought. By then, the Trinitarian doctrine articulated at the Council of Nicaea (325) had undergone extensive processes of reception, assimilation, and reformulation within the context of Patristic reflection.

Thus, in Augustine’s time, the “Nicene faith” was more closely tied to the regula fidei—the objective standard of the Church’s faith—than to the specific formulations of the original council. In Augustine’s own theological development, particularly in his seminal work De Trinitate, we witness a gradual maturation culminating in a theological synthesis of extraordinary depth and sophistication.

More than simply being “challenged” by Nicaea, Augustine and his spiritual heirs assumed the ecclesial responsibility of safeguarding a profound historical and religious legacy—one that has decisively shaped the contours of Western culture. This inheritance has left an indelible mark across numerous domains—tradition, art, liturgy, literature, science, architecture, politics, and even our conception of the human spirit. Preserving this legacy is therefore an essential task for the memory and identity of the Order of Saint Augustine, and by extension, for the Church as a whole.