In his response to the joint Catholic-Orthodox declaration, Metropolitan Philaret of the ROCOR states that union with Rome is only possible if "they accept the Orthodox Faith as it is maintained until now in the Holy, Catholic, and Apostolic Church." 1

Absent from that final phrase is mention of the Mark of Oneness or Unity, which, of course, is a thing accepted by the Eastern Orthodox churches as they hold to the Nicene Creed (the 4 being mentioned, in addition to Orthodox, by Fr. Seraphim Cardoza here) which states:

[We Believe in] one holy, catholic, and apostolic Church 3

Of the Mark of Unity, the Catholic Encyclopedia says that:

The marks of the Church are certain unmistakeable signs, or distinctive characteristics which render the Church easily recognizable to all, and clearly distinguish it from every other religious society, especially from those which claim to be Christian in doctrine and origin.

[the Church which has Christ for its founder] must unite its members in unity of doctrine[...] in unity of worship[...] and in unity of government. 4

That's the Catholic Encyclopedia, though. I'm looking for Orthodox sources. The Wikipedia article doesn't really talk about the Orthodox perspective. The OrthodoxWiki does not have an article on either the Four Marks, or of Unity as a Mark. Is my phrasing the problem? Should I be using different words? What are some sources from Eastern Orthodoxy about the 4 Marks and/or specifically about the Mark of Unity.

As of 08-Mar-2022 I found that there is [this article][https://orthodoxwiki.org/Primacy_and_Unity_in_Orthodox_Ecclesiology] on OrthodoxWiki that has a couple sources to use. Namely Metropolitan John Zizioulas, Fr. John Meyendorff, Fr. Alexander Schmemann, and Fr. Thomas FitzGerald. But it seems I'll need to simply read their works for a non-wiki answer.

  • the multiplicity of churches within that communion - Are you referring to the existence of national church structures absent in Catholicism ? (i.e., the French and the Spanish are both Catholic, but there is no French Catholic Church or Spanish Catholic Church to speak of). Or to the existence of various schismatic or heretical groups bearing the term orthodox in their name or title ? (e.g., Old Calendarism, Oriental Orthodox, etc).
    – Lucian
    Aug 12, 2021 at 10:32
  • The former. I mean that there's the Russian church, the Greek church, etc. And some are autonomous while some are not, and some are recognized and some are not, and not all are in communion with each other (namely Moscow and Cnple) Aug 12, 2021 at 13:29
  • Numerically speaking, the overwhelming majority of Orthodox Christians belong to a few usually-independent national churches, situated in Eastern Europe, and accounting for about a quarter-billion people. The rest are numerically insignificant. (Does this help paint a clearer picture ?)
    – Lucian
    Aug 12, 2021 at 13:55
  • 1
    If numbers would not be important, then we might as well speak of the fictional religions from Game of Thrones, whose membership count, in the real world, is zero. Eastern Orthodoxy is basically the common religious faith of hundreds of millions of people from Eastern Europe, just as Roman Catholicism is the common pre-Protestant religious faith of hundreds of millions of people living in the western world; the existence of various minorities or fringe groups whose Orthodoxy or Catholicism is uncertain does not cancel or annul the existence of a strong backbone.
    – Lucian
    Aug 12, 2021 at 14:32
  • 1
    I thought it might help you get a clearer perspective of what the Orthodox church is.
    – Lucian
    Aug 12, 2021 at 17:29

1 Answer 1


What you are looking for I believe can be found in distilled form in the The Longer Catechism of The Orthodox, Catholic, Eastern Church authored by Philaret of Moscow in the 19th century. Look specifically at Articles 268-276.

  • That's a good start. But "distilled" is an understatement. Is there any work that expounds further on this catechism itself? Mar 22 at 2:52

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