“I believe … In one, holy, catholic and apostolic Church. I confess one baptism for the forgiveness of sins.” (The Nicene Creed)
The Church is one. Since she is the living Body of Christ and Christ is one, so the Church cannot be anything but one. Indeed, it was for this reason that the Lord came; to unite us with God and each other - a unity that had been severely shaken after the fall of Adam and Eve and their obedience to the devil whose aim was none other than to separate us from God and our fellow man. The Lord came so as to call us all to unite, and the place where this two-fold unity is achieved is the Church, His theanthropic Body. In the Church we are united with God and our brothers, since we became members of the same Body.
Thus, every breakaway and separation from the one Church means opposition to the saving work of the Lord and separation from His Grace. It is nothing other than an insult against the Holy Spirit which holds together the institution of the Church and constitutes Its unity. However, in such cases the devil deceives men using various justifications which, at first, may seem plausible, such as their founding a church which will be more genuine, more traditional, more Orthodox, more strict, which will keep the old calendar and so on. But the result is their separation from the Church and consequently from the saving Grace of the Holy Spirit. At the same time they come into conflict with the whole practice and history of the Church and the whole content and meaning of Her Holy Canons. “After the heresies the devil tried to use the frenzy of schismatics to divide the Body of Christ. For this reason all those who follow a schismatic, be they monks or lay people, are totally excommunicated from the Church until they come to detest their contact with the schismatics and return to their own Bishop” (The Rudder, p. 357).
We have, for instance, the period of Iconoclasm, during which the Church was in turmoil for some 150 years, but the Holy Fathers who struggled on behalf of Orthodoxy did not create another church. Instead they themselves became martyrs and confessors of the Orthodox Faith and, in the end, Orthodoxy triumphed without the unity of the Church being broken. At times, the Lord may allow the Church to be tried in different ways “so that those who are genuinely of us might be made manifest” (1 Cor. 11:19), as the Apostle says, but the Church can never be misled, since it is the living Body of the Theanthropos Christ. Hence, there can be no justification whatsoever for those who for whatever reason separate themselves from the Church. “Heresies and schisms constitute sins of types that are particularly grave and difficult to heal. They, also, constitute the means through which the devil tries to impede men’s salvation by cutting them off from life-giving communion with the Church” (Archimandrite George Kapsanis, Pastoral Duties According to the Holy Canons, p. 187, Piraeus, 1976).
Something similar is true of those Christians who, without openly separating themselves from the Church, establish small groups, alien to the Spirit of the Church. They imagine themselves to be the only guardians of Orthodoxy, while everyone else including Bishops and Priests are indifferent or even betrayers of Orthodoxy. In being fanatically devoted to particular persons and societies, they alienate themselves from the Body of the Church, which from the beginning, has been expressed by the Divine Liturgy and the parish and not societies. They resist the work of unity for which the Lord was crucified and estrange themselves from the Orthodox ethos, which is full of humility, meekness, obedience and love. In this way, they fall into that which St Paul criticises in his first epistle to the Corinthians, “that everyone of you saith, I am of Paul; and I of Apollos; and I of Cephas; and I of Christ. Is Christ divided?” (1:12-13).
On the Holy Mountain (Mount Athos) we follow the Old Calendar without ever-breaking away from the Church and naturally we commemorate the Ecumenical Patriarch since it is to his ecclesiastical jurisdiction that we belong. Whenever bishops or priests of the Church who follow the new calendar come, they celebrate with us in our Monasteries and similarly when we are outside the Holy Mountain, we celebrate in their canonical Churches. Different practices regarding secondary matters always exist in the Church without their ever being the cause of schisms.
From the book The Land of the Living, Mount Athos, 1987.