In the third section of this third chapter of Being as Communion, Metropolitan Zizioulas proceeds to discuss four implications of the synthesis between Christology and Pneumatology for ecclesiology.

The first of these, the importance of the local Church in ecclesiology, has been emphasised in the “eucharistic ecclesiology” associated with N. Afanasiev, but has not yet been justified in terms of Pneumatology, a task which Zizioulas proceeds to attempt.

The Church as the Body of Christ is instituted through the Christological event and owes her being to the one Christ. This could mean that there is first one Church and then many Churches, as Rahner has argued, seeing the “essence” of the Church in the universal Church. However, if we view Pneumatology as constitutive of both Christology and ecclesiology, then we cannot speak in these terms, for

The Pentecostal event is an ecclesiologically constitutive event. The one Christ event takes the form of events (plural), which are as primary ontologically as the one Christ itself. The local Churches are as primary in ecclesiology as the universal Church. No priority of the universal over the local Church is conceivable in such an ecclesiology. (133)

However, there is also a danger of prioritising the local Church over the universal, a danger resulting from the lack of a proper synthesis between Christology and Pneumatology. This mistake – made by Afanasiev and some Orthodox theologians – is a mistake

because the nature of the eucharist points not in the direction of the priority of the local Church but in that of the simultaneity of both local and universal. There is only one eucharist, which is always offered in the name of the “one, holy, catholic and apostolic Church.” The dilemma “local or universal” is transcended in the eucharist, and so is any dichotomy between Christology and Pneumatology. (133)

This leads to the question of what ecclesial structures help to maintain this balance between the local and the universal, and hence to the second implication, namely, the significance of conciliarity.

While Orthodoxy does not have a  pope, it is a mistake to see it as having councils instead of a pope. Instead, conciliarity is rooted in the idea of communion, which is an ontological category in ecclesiology and Zizioulas sees this as rooted in the Trinitarian theology of the Cappadocian Fathers.

One of the striking peculiarities of St. Basil’s teaching on God, compared with that of St Athanasius and certainly with that of the Western Fathers, is that he seems to be rather unhappy with the notion of substance as an ontological category and tends to replace it – significantly enough for our subject here – with that of koinwni/a. Instead of speaking of the unity of God in terms of His one nature, he prefers to speak of it in terms of the communion of persons: communion is for Basil an ontological category. The nature of God is communion. This does not mean that the persons have an ontological priority over the one substance of God, but that the one substance of God coincides with the communion of the three persons. (134)

In the same way, while there is one Church, “the expression of this one Church is the communion of the many local Churches. Communion and oneness coincide in ecclesiology.” (135) It therefore follows that the institution that expresses the oneness of the Church must also express communion and that “the institution of universal unity cannot be self-sufficient or self-explicable or prior to the even of communion; it is dependent on it.” (135) In the same way, however, communion cannot be prior to the oneness of the Church and “the institution which expresses this communion must be accompanied by an indication that there is a ministry safeguarding the oneness which the communion aims at expressing.” (135)

Instead of viewing the synod as a democratic alternative to “monarchical” Rome, as is sometimes thought, the significance of the synod for in Orthodox tradition can be found in canon 34 of the Apostolic Constitutions. This insists on the principle of one head in each province. The local bishops-Churches cannot do anything without the “one” but, at the same time, the “one” cannot do anything without the “many”. Thus “There is no ministry or institution of unity which is not expressed in the form of communion. There is no ‘one’ which is not at the same time ‘many'”. (135-136)

Orthodox ecclesiology requires an institution that expresses the oneness of the Church. However,

the multiplicity is not to be subjected to the oneness; it is constitutive of the oneness. The two, oneness and multiplicity, must coincide in an institution which possesses a twofold ministry: the ministry of  prw=tov(the first one) and the ministry of the “many” (the heads of the local Churches). (136)