EOs and OOs are very close in traditions and have ancient Christian roots. They are two great communities of Christians in the East. Ideally, they should resolve their differences correctly and reunite. Over the last 1500+ years major, yet unsuccessful, attempts have occurred.
There are really two fundamental obstacles: 1. The debate over the number of natures, and 2. the debate over whether the EO Ecumenical Councils 4-7 must be accepted for reunion.
1. Normally in Christian dialogue one should just be able to define a term and then apply that meaning to common beliefs. But in practice EOs and OOs break down over this.
According to dictionaries, "nature"(physia) means a category, a collection of properties, an essence, or a substance. In Paul's letters, it means a "category", as when he writes that God made man the master of "every nature (physia) of beast". EOs and OOs agree that Christ has two essences and substances, and that he is in two categories: that of man and of God. Further, he has two collections of properties: divine properties and human ones. Therefore, purely as a matter of logic, both sides should agree that Christ is in two natures and has two natures. My own experience has been that a major portion of OOs can understand and accept this.
However, rejection of the two natures remaining in Christ goes back to the Alexandrian Patriach Dioscorus' deposal of Flavian. This was after St. Cyril had already reunited with John Antiochene and settled their differences over the number of "natures", but before Chalcedon. At Chalcedon, Dioscorus said: "The reason why Flavian was condemned was plainly this, that he asserted two natures after the incarnation." (SOURCE: http://www.ccel.org/...h of Alexandria)
Some OOs today object that "nature" means something like hypostasis or entity, and that saying "in two persons" divides him into two separate entities. However, this is not really the meaning of "nature", since OOs and EOs would agree that God is n three hypostases, but not in three natures. Further, Chalcedon's Creed says that Christ is in one hypostasis and two natures, so "hypostasis" is not what Chalcedon meant by "natures."
Since EOs and OOs agree that Christ has two collections of properties, that he is in two categories, that he has two essences, that he is one being and one hypostasis and one person, I don't see a real substantive difference between EOs and OOs on the Christological issue other than the semantic issue of "natures". Once the word "nature" is taken out of the discussion, the two sides generally agree on the substance of their christologies.
I don't find a rational basis for dispute between our churches on this issue. But I am well aware that a major portion of OOs intensely opposes the idea of Chris being "in two natures." You can spend hours discussing it with that faction and won't make major progress resolving the semantic issues. They repeat that the phrase "in two natures" means that the entity is divided into two entities.
I disagree that as a matter of language to say something has or is in two natures means that it's divided. Take for example this quote in common language: "Schopenhauer is quite explicit that the world is only to be understood in two natures: namely, representation and will." (Source: https://jordanalexan...dpress.com/91-2) Schopenhauer is not speaking of "two worlds" even though he uses the phrase "in two natures".
For me, this issue is incredibly simple as a matter of logic that debating it looks irrational. It's like debating whether a bottle is half empty or half full. Yet I have seen Russians debate an Armenian for months over maybe 100 pages of messages on Christology. Our churches have debated this for 1500+ years, and somehow they don't "get it". Personally, I think it's ideological, whereby their minds lock into a certain interpretation because it's fundamental to their community. In those kinds of discussions, I'm not angry, just frustrated like trying to argue for days constantly that a bottle of water filled 6 ounces out of 12 is half full.
This gives rise to the next question:
2. Is Chalcedon so important that we must require it as a basis for reunion?
John of Antioch and St. Cyril reunited without St. Cyril fully explicitly affirming that Christ "is in two natures." St. Cyril said things that in my view amount to that, but his statements haven't been explicit enough to persuade a major portion of OOs today.
One of the obstacles though was that even though they had this resolution, the reunion didn't stop P. Dioscorus from deposing Patriarch Flavian for saying Christ still had two natures. If we don't agree as part of our reunion today that "in two natures" is acceptable, then we can be back where we were in 440-450 AD when Flavian was wrongly deposed, since a major portion of OOs still thinks that "in two natures" is heretical.
Secondly, Ecumenical Councils are pillars for defining Orthodoxy. Is it really acceptable to downgrade an Ecumenical Council because its opponents semantically misunderstand its conceptually correct main faith statement?
Would OOs agree to calling Nicea or any other of their Ecumenical Councils merely local, non-Ecumenical ones because a Christian group misunderstood a term in the Council's main declaration? For example, St. Athanasius at one point said that God "made" Jesus in the sense of performing the incarnation. So imagine if a Trinitarian group rejected the Nicene Creed because they misunderstood its semantics and felt that saying that Jesus was "not made" denied his incarnation. Would the OOs be willing to say that Nicea was not a basis for reunion with the Trinitarian group, who didn't understand the terms "not made" in their context?
Edited by H. Smith, 01 April 2016 - 09:20 AM.