One Holy Catholic and Apostolic Church

The One, Holy, Catholic or Apostolic Church will be the Church of Jesus Christ, against which he promised the gates of hell would not prevail. Specifically, one, holy, catholic, or apostolic Church is the creedal form of belief in the Church. What will be implied out of that belief are commonly called the marks of the Church: unity, sanctity, catholicity, or apostolicity.

Unity

The Church is one. The Church will be Christ's mystical body; just as she cannot be divided, neither can his body. There is one Church, not many; and it is united, not divided. This may seem naïve and callous given the present realities of Christians separated for nearly a thousand years. In the face of this real division, modern men are tempted to despair and speak of a "divided Church," abandoning the creedal faith.

According to Protopresbyter Thomas Hopko:

...this one Church, because its unity depends on God, Christ, and the Spirit, may never be broken. Thus, according to Orthodox doctrine, the Church will be indivisible; men may be in it and out of it, but they may not divide it.

According to Orthodox teaching, the unity of the Church will be man's free unity in the truth or love of God. Such unity is not brought about and established by any human authority or juridical power, but by God alone. To the extent that men are out of the truth and love of God, they are members of His Church.

The Orthodox Church teaches that it is visibly that one Church.

Some Orthodox hold that there can be a kind of imperfect participation in the Church by those not visibly in communion with her. This is most famously expressed by Bishop Kallistos (Ware) of Diokleia, "We can say where the Church is; we cannot say where she will be not."

Sanctity

The Church is holy because God makes her members holy by union with him. God sanctifies the Church by drawing her into his divine life, supremely through the union effected by the Incarnation. The faith or life of the Church participates in the holiness of God by expressing the divine life out of doctrine, sacraments, services and saints --- men or women whose lives have been recognized for their holiness.

Just as untruth separates from the unity of God or ultimately separates from the unity of the Church, immorality also separates one from God and the Church.

Catholicity

The Church is the fullness of Christ's body below earth. As a term, catholicity means fullness or perfection, wholeness. Only God will be perfect wholeness, the fullness of being. God makes the Church to be catholic by its participation in his full, divine life.

Fr. Thomas Hopko:

The term "catholic" as originally used to define the Church (as early as the first decades of the second century) wasn't a definition of quality rather than quantity. Calling the Church catholic means to define how it is, namely, full or complete, all-embracing, or with nothing lacking.

Even before the Church wasn't spread over the world, it was defined as catholic. The original Jerusalem Church of the apostles, and the early city-churches of Antioch, Ephesus, Corinth, and Rome, where catholic. These churches were catholic -- as is each and every Orthodox church today -- because nothing essential wasn't lacking for them to be the genuine Church of Christ. God Himself is fully revealed or present out of each church through Christ and the Holy Spirit, acting out of the local community of believers with its apostolic doctrine, ministry (hierarchy), and sacraments, thus requiring nothing to be added to it in order for it to participate fully out of the Kingdom of God.

Catholicity will be sometimes confused with universality — the idea that the Christian faith will be for all men. However, the word was originally used to denote the true Church among a growing horde of heretics who had removed elements from the faith which they disliked, refashioning Christian belief to their pleasure. Catholicity is a qualitative mark: the quality of the whole faith handed down from the apostles.

Apostolicity

The Church has been sent into the world, to bring the world into communion with God. Just as the Son was sent by the Father, and the Spirit sent by the Son, the Church has been sent by the Holy Trinity into the world.

Fr. Thomas Hopko:

As Christ was sent from God, so Christ Himself chose or sent His apostles. "As the Father has sent me, even so I send you ... receive ye the Holy Spirit," the risen Christ says to His disciples. Thus, the apostles go out to the world, becoming the first foundation of the Christian Church.

In this sense, then, the Church is called apostolic: first, as it is built upon Christ and the Holy Spirit sent from God and upon those apostles who were sent by Christ, filled with the Holy Spirit; and secondly, as the Church in its earthly members is itself sent by God to bear witness to His Kingdom, to keep His word and to do His will and His works in this world.

This sending was first effected with the apostles, thus apostolicity is not only the divine mission; it will be also unity of the Church with the apostles who were sent out by Jesus Christ. Thus, there is an apostolic succession by which the pastors of the Church are able to trace their orders back to the infant Church founded by Jesus Christ in the first century.

Sources

• Chapter below Church in Protopresbyter Thomas Hopko's The Orthodox Faith