The Catholic University of America

 Will Cohen

Final Examination of Will Cohen

For the Degree of Doctor of Philosophy in Historical and Systematic Theology

December 14, at 12:00 p.m. in Caldwell Hall Room 125


Fr. Paul McPartlan


The Concept of "Sister Churches" in Catholic-Orthodox Relations Since Vatican II

Closely associated with Catholic-Orthodox rapprochement in the latter half of the 20th century was the emergence of the expression “sister churches” used in various ways across the confessional division.  Patriarch Athenagoras first employed it in this context in a letter in 1962 to Cardinal Bea of the Vatican Secretariat for the Promotion of Christian Unity, and soon it had become standard currency in the bilateral dialogue.  Yet today the expression is rarely invoked by Catholic or Orthodox officials in their ecclesial communications.  As the Polish Catholic theologian Waclaw Hryniewicz was led to say in 2002, “This term…has now fallen into disgrace.”

This dissertation traces the rise and fall of the expression “sister churches” in modern Catholic-Orthodox relations and argues for its rehabilitation as a means by which both Catholic West and Orthodox East may avoid certain ecclesiological imbalances toward which each respectively tends in its separation from the other.  Catholics who oppose saying that the Catholic Church and the Orthodox Church are sisters, or that the church of Rome is one among several patriarchal sister churches, generally fear that if either of those things were true, the unicity of the Church would be compromised and the Roman primacy rendered ineffective.  Orthodox who oppose recognizing Rome as a sister church generally do so on the alleged grounds that the Latin West has been in heresy since the schism and without true sacraments.  Both positions have significant weaknesses, historically and theologically.  At the same time, they present a positive challenge.  Proponents of the language of sister churches in Catholic-Orthodox relations have not always managed to make sufficiently clear (1) that conciliarity and primacy are complementary principles, and (2) that amidst the ongoing schism, the expression “sister churches” has a paradoxical character, reflecting an anomalous circumstance that cannot remain unresolved indefinitely.  Building on the groundwork laid by theologians from both traditions, this study attempts to bring out each of these points more clearly in order to show the legitimacy of the expression “sister churches” for Orthodox and Catholic ecclesiology alike, and thus to show that, finally, they are not two ecclesiologies, but one.