stylistic:tone
Catholicity

The Eastern Orthodox Church considers itself to be both orthodox and catholic. The doctrine of the Catholicity of the Church, as derived from the Nicene Creed, is essential to Eastern Orthodox ecclesiology. The term Catholicity of the Church (Greek Καθολικότης τῆς Ἐκκλησίας) is used in its original sense, as a designation for the universality of the Christian Church, centred around Christ. Therefore, the Eastern Orthodox notion of catholicity is not centred around any singular see, unlike the Catholic Church which has one earthly centre.

Due to the influence of the Catholic Church in the west, where the English language itself developed, the words "catholic" and "catholicity" are sometimes used to refer to that church specifically. However, the more prominent dictionary sense given for general use is still the one shared by other languages, implying breadth and universality, reflecting comprehensive scope. In a Christian context, the Christian Church, as identified with the original church founded by Christ and his apostles, is said to be catholic (or universal) in regard to its union with Christ in faith.

Just as Christ is indivisible, so are union with him and faith in him, whereby the Christian Church is "universal", unseparated, and comprehensive, including all who share that faith. Orthodox bishop Kallistos Ware has called that "simple Christianity". That is the sense of early and patristic usage wherein the church usually refers to itself as the "Catholic Church", whose faith is the "Orthodox faith". It is also the sense within the phrase "one, holy, catholic, and apostolic Church", found in the Nicene Creed, and referred to in Orthodox worship, e.g. in the litany of the catechumens in the Divine Liturgy.

With the mutual excommunications of the East–West Schism in 1054, the churches in Rome and Constantinople each viewed the other as having departed from the true church, leaving a smaller but still-catholic church in place. Each retained the "Catholic" part of its title, the " Roman Catholic Church" (or Catholic Church) on the one hand, and the " Orthodox Catholic Church" on the other, each of which was defined in terms of inter-communion with either Rome or Constantinople. While the Eastern Orthodox Church recognises what it shares in common with other churches, including the Catholic Church, it sees catholicity in terms of complete union in communion and faith, with the Church throughout all time, and the sharing remains incomplete when not shared fully.