Yves Congar regarded John Zizioulas, who died on February 2 at the age of ninety-two, as “one of the most original and profound theologians of our epoch.” Kallistos Ware believed he was “generally recognized as the most brilliant and creative theologian in the Orthodox Church today.” Pope Francis once called him “the greatest Christian theologian of our generation.”

I recall my enthusiasm at first encountering the work of John Zizioulas as a young theology student in Athens. It was an article on the theological foundation of personhood titled “From Mask to Personhood”—originally published in Greek in 1977 and translated as the opening chapter of his first collection of articles in English, Being as Communion (St. Vladimir’s Orthodox Press, 1985). At the time, Zizioulas was teaching systematic theology at the University of Glasgow. He was also a fresh Orthodox voice in the contemporary ecumenical movement, serving on the staff of the World Council of Churches’ Commission on Faith and Order. I first met him exactly thirty-two years ago, when he attended the seventh General Assembly of the WCC in Canberra. After his election and ordination to the episcopate in 1986, when he received the title Metropolitan of Pergamon (one of the seven churches in the Book of Revelation), Zizioulas chaired the International Commission for Orthodox-Anglican Theological Dialogue (1989–2007) and the Joint International Commission for Theological Dialogue between the Orthodox and Roman Catholic Churches (2005–2016).

Before all that, Zizioulas had completed a doctoral dissertation at the University of Athens on The Unity of the Church in the Eucharist and the Bishop During the First Three Centuries (1965, revised in 1990), later published in English as Eucharist, Bishop, Church (Holy Cross Orthodox Press, 2001). He also taught as professor of theology at various schools, including King’s College and the University of Thessaloniki, before retiring from academic teaching in 1998. However, he continued speaking and publishing until his death. There have been several collections of his lectures and articles: Communion and Otherness: Further Studies in Personhood an the Church (ed. Paul McPartland, T&T Clark, 2006); Lectures in Christian Dogmatics (ed. Douglas Knight, T&T Clark, 2009); The One and the Many: Studies on God, Man, the Church, and the World Today (ed. Gregory Edwards, Sebastian Press, 2010); The Eucharistic Communion and the World (ed. Luke Ben Tallon, T&T Clark, 2011); and Priests of Creation: On Discerning an Ecological Ethos (ed. John Chryssavgis and Nikolaos Asproulis, T&T Clark, 2021). Zizioulas’s magnum opus on eschatology, most of which he had completed prior to his death, will be published posthumously.

The core of Zizioulas’s theology is captured in the title of a comparative study by Paul McPartlan, The Eucharist Makes the Church: Henri de Lubac and John Zizioulas in Dialogue (T&T Clark, 1993), which explores the complementary nature of Eastern and Western theology in relation both to the unity in the church and the challenges of the modern world. More recently, Aristotle Papanikolaou (of Fordham University) published a comparative study of Vladimir Lossky and John Zizioulas titled Being with God: Trinity, Apophaticism, and Divine-Human Communion (Notre Dame Press, 2006). Numerous studies and dissertations on the theology of Zizioulas have appeared in the years since.

I was privileged to work closely with Metropolitan John in various ministries. As a senior prelate of the Ecumenical Patriarchate, Zizioulas chaired the fourth (2014) and fifth (2015) Panorthodox Preconciliar consultations held in Geneva to prepare for the Holy and Great Council, which convened in Crete in 2016. This was the first expansive assembly of Orthodox bishops in over a thousand years. Despite relentless resistance from some churches—abetted by the Patriarchate of Moscow and its cantankerous delegation—Metropolitan John demonstrated his unique aptitude and integrity in guiding the member churches to commit to conversation with one another for the sake of a unified witness to the world. This, he believed, was the unique vocation of the Ecumenical Patriarchate. In a lecture delivered in Athens in 2013, Metropolitan John observed:

An institution survives only when it discerns the heartbeat of history and responds to the existential demands of the world. This is the essential mission of the Ecumenical Patriarchate today and tomorrow. If this institution did not exist, then it ought to have been discovered. Without the Ecumenical Patriarchate, Orthodoxy would be constrained to maelstrom of ethnocentrism, triumphalism, introversion, and contempt for the contemporary world.

As senior spokesman for the Ecumenical Patriarchate on ecological matters, Zizioulas attended the 1988 conference on the island of Patmos that proposed to then Ecumenical Patriarch Demetrios (1914–1991) that September 1 should be dedicated as a day of prayer for the protection and preservation of the natural environment. This dedication became official in 1989 and was soon thereafter adopted by the World Council of Churches and the Conference of European Churches, as well as the Roman Catholic Church and the Anglican Communion. Zizioulas’s systematic ecological reflection began around the same time, with three groundbreaking lectures delivered at King’s College and later published in King’s Theological Review (volumes 12–13, 1989–1990). He also co-chaired (with Dr. Jane Lubchenco) the Religion and Science Committee of the Ecumenical Patriarchate, which led to a series of international, interfaith, and interdisciplinary symposia on major seas and rivers—from the Mediterranean and the Arctic to the Danube and the Mississippi—aimed at raising awareness of the ecological crisis. All this activity led to Ecumenical Patriarch Bartholomew being widely regarded (and not only in the Orthodox Church) as the “green patriarch.”

What I always admired most about Zizioulas was his eagerness for encounter and engagement with other confessions and other disciplines, especially with science and art. He was convinced that, without such openness to dialogue, Orthodoxy was destined to become little more than a ghetto on the margins of society. When, in 2017, Ecumenical Patriarch Bartholomew appointed a special commission of clergy and lay theologians to create a document on an Orthodox approach to contemporary social issues—echoing the message of the Great Council, while reflecting the tradition and practice of the Church of Constantinople—Zizioulas admitted that, while such an initiative had never previously been undertaken in the Orthodox Church, it nevertheless had a legitimate place in the vision of the Ecumenical Patriarchate. Like his counterpart Metropolitan Kallistos Ware (1934–2022), Zizioulas offered invaluable comments, particularly on the sections pertaining to sexuality and the environment, before the final text was published in 2022 under the title For the Life of the World: Toward a Social Ethos of the Orthodox Church.

There is no doubt that Zizioulas’s theological, ecumenical, and ecological legacy will endure for decades to come. He was more than a great theologian. He was a leader at a critical moment in the history of the Orthodox Church.