Participants in the 16th Ecclesiological Investigations International Research Network, “Dissent, Power, and Christian Unity after Nicaea.”
The 16th Ecclesiological Investigations International Conference was held September 17-20, 2025, in Thessaloniki, Greece, contributing to this year’s many events commemorating the 1700th anniversary of the First Council of Nicaea, convened in 325 AD by the Emperor Constantine I. Given that Nicaea took place at a time of remarkable religious pluralism and diversity and was convened in response to the disputes over “what is the Church” within that context, that early ecclesial reality shares an important resonance with our current historical moment. The purpose of the 2025 Ecclesiological Investigations conference was to pose the questions: In what ways does Nicaea continue to shape how we configure the Church today, with what opportunities and at what cost?
Advancing Global Dialogue in Theology and Interreligious Studies
Dr. Aaron Hollander, Br. Yasser Zamora, SA, and a group of Graymoor Scholars past and present.
The Ecclesiological Investigations International Research Network came into being in 2005, first as a Program Unit of the American Academy of Religion (AAR) and soon expanding into international conferences, a book series with Palgrave MacMillan, collaborations with journals (including Ecumenical Trends), and online symposia. Since 2022, Graymoor Ecumenical & Interreligious Institute (GEII) has been a regular co-organizing and co-sponsoring partner on major EIIRN events. GEII Executive Director, Aaron Hollander, served as Chair of the Thessaloniki 2025 organizing committee: introducing the conference, moderating its opening plenary session, and offering summary remarks during its final dinner. He also oversaw the awarding of this year’s Graymoor Scholarships, supporting the participation of four exceptional graduate students working in ecumenical and interreligious field, whose work will be published in an upcoming issue of Ecumenical Trends. Read more about the 2025 Graymoor Scholars at Graymoor Scholarship.
Highlights of the conference’s academic proceedings included its four main plenary sessions, during which participants heard substantial lectures from distinguished scholars of church history, theology, contemporary ecumenism, and interreligious studies. These included: “Sophia’s Banquet: Christian Identity, Dissent, and Power,” by the Rev. Dr. Leo Lefebure (Georgetown University); “The Council of Nicaea: Inspiration for Those Seeking Unity Today,” by the Rev. Susan Durber (World Council of Churches); “The Wound of Christian Identity in Times of Division,” by Sr. Dr. Geraldine Smyth (Irish School of Ecumenics, Trinity College Dublin); and “Divine Word and Spirit in a Human Body? ʿIsā ibn Maryam and the Interreligious Debate between Islam and Eastern Christianity,” by Dr. Marco Demichelis (University of Bologna). Video recordings of the plenary lectures are available at Ecclesiological Investigations Page.
Visit to Mount Athos and Reflections on Ecumenical Collaboration at Thessaloniki
Dr. Hollander aboard the boat tour along the Athos Peninsula.
On the conference’s final day, participants had the remarkable opportunity to visit the “Holy Mountain” of Mount Athos. Since 1054, the Athos peninsula has been the site of an autonomous “monastic republic,” free from external governance by Byzantine, Ottoman, or modern Greek administrations, where the spiritual heritage of Orthodox Christianity has been preserved and developed. Conference participants boarded a boat in Ouranoupoli that traversed the southern coast of the peninsula, visiting with monks from Xenophontes Monastery and providing a profound experience to all involved.
Brother Yasser Zamora, SA, participated in Thessaloniki 2025 as a representative of the Franciscan Friars of the Atonement, offering one of the conference’s opening prayers and making many new connections among scholars and practitioners across the Christian world.
He writes: “To gather in Thessaloniki for this Ecumenical meeting was to experience the biblical vision of ‘At-One-Ment’ made tangible. It was an intellectual and vicennial journey through the history of the Nicene Creed, but more profoundly, it was a spiritual encounter with the unbroken whole of the Body of Christ. I recall the warmth of shared coffee breaks, the prayers and the intensity of theological debate, seeing men and women from Orthodox, Catholic, Anglican, and Protestant traditions—from every corner of the world—united by the singular purpose of answering Christ’s prayer for unity. As we talked, prayed, and reflected, the city of Paul itself seemed to whisper a powerful message: Our differences are not obstacles; they are the Spirit’s gifts, enriching the common truth we share. These pictures capture the faces, the light, and the places where we realized that the necessity of Christian unity is, above all, a work of love and mutual hospitality.”
We celebrate the ongoing, fruitful partnership between GEII and EIIRN, and we look forward to the 17th Ecclesiological Investigations International Conference, to be held in 2027 in Temuco, Chile.