His capacity as acting Metropolitan of the Ecumenical Throne, although it did not substantially interfere with his academic activity, added to John Zizioulas ecclesiastical responsibilities, which in one form or another did not cease to be connected to his capacity as a systematic theologian. Thus, his status as a theologian served his ecclesiastical activity, while his ecclesiastical activities contributed, together with other previous contributions to the Church, to the further development, theoretical deepening and practical application of his knowledge and research as a systematic theologian. From these ecclesiastical activities, which are directly related to his status and research as a systematic theologian, we cite the following as examples:

a) Presidency of the International Committee of the Official Theological Dialogue of the Orthodox Church with the Anglican Church

b) Representative of the Ecumenical Patriarchate in the international committee of the official Theological Dialogue between the Orthodox and the Roman Catholic Church

c) President of the Orthodox Committee for the Protection of the Natural Environment

d) President of the Pre-Orthodox Preparatory Committee of the Great and Holy Synod of the Orthodox Churches

e) Contribution to the theological Commission “Faith and Order” of the World Council of Churches

f) Speaker at Lambeth Conference of Anglican Bishops

These points are only indicative elements of the ecclesiastical activity of John Zizioulas, and were selected based on the criteria of their relation to the cultivation and promotion of Orthodox theology internationally. His use as theological advisor of the Ecumenical Patriarchate was continuous and did not end in the above listed points. Alongside these theological activities, the Patriarchate entrusted him with responsible ecclesiastical missions.