Ecumenism is, principally, dialogue between Christian denominations aimed at promoting the restoration of unity among all Christians through understanding, through mutual respect and toleration, and through practical cooperation in areas of common concern.
Orthodox Christians take widely different attitudes toward ecumenism. A few embrace the Anglican "branch theory" which implies that the various divisions in Christianity all represent branches of the same Church just as the branches of a tree are all integrally part of the same living tree. Many object to this theory on the ground that it tends to minimize Orthodoxy, reducing its stature as exclusively the one holy catholic and apostolic Church to that of a relatively small segment of the Church. Some regard ecumenism as an opportunity to present Orthodoxy as a unique witness to the ancient Christian faith and to the Church as the indivisible body of Christ. Others feel that ecumenism necessarily undermines this witness and feel that Orthodoxy will be forced to alter traditional practices and even the very content of the ancient apostolic faith. In the Twentieth Century particularly, some ecumenical activities have drawn sharp criticism from various voices within the Orthodox Church, particularly participation in the World Council of Churches and the National Council of Churches in the US. Those opposing ecumenism are often self-labelled as Traditionalists and may be either within or outside mainstream Orthodoxy, particularly within the Old Calendarist movements, who often regard the New Calendar as being a symptom of "branch theory" ecumenism.
One of the more controversial documents drawn up in recent years pertaining to ecumenism is the Balamand Statement, an unofficial joint document of recommendation on Uniatism signed by representatives of the Orthodox Church and the Roman Catholic Church in 1993.
- Ecumenical Guidelines for SCOBA
- Baptism and "sacramental economy": An agreed statement of the North American Orthodox-Catholic Theological Consultation - Saint Vladimir's Orthodox Seminary, Crestwood, New York - June 3, 1999
- Ecumenism: Origins - Expectations - Disenchantment, September 2004 Conference on Ecumenism, held at Aristotle University, Thessaloniki, Greece
- Conclusions of the Conference on Ecumenism
- The Church of Serbia vis-à-vis Ecumenism, by Bishop Artemije of Raska and Prizren
- Contours of Conversion and the Ecumenical Movement, by Hieromonk Alexis (Trader) of Karakallou
- The Consequences of Orthodox Participation in the Ecumenical Movement on the Orthodox Witness to the Heterodox West, by Fr. John Reeves
- The Mystery of Baptism and the Unity of the Church, by Fr. Peter A. Heers