Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
The mixture of two material substances is not a good analogy for the incarnation. The one which the Fathers more often use is that of fire and iron.
Amen. Even the Indian theologians use this same analogy to explain theosis by proxy. The Divine Nature is inaccessible to our mortality, as Its Self-Existing, whereas we depend upon It for our existence. The Indians, like the Cyrillian fathers, use the analogy of the ignited iron to explain how, while the Divine is beyond the physicality of our own material substance, we can be directly affected by the Divine and experience It just as the material Iron is heated by the Flame, which is itself immaterial. The Heat is not necessarily a substance of its own which unites through subsistence with the Iron, rather the atoms of the Iron are excited by the force of the Heat, and the Iron ignites. The Heat remains unaffected (in this model, we know in science that heat is a force which dissipates over time, whereas the Divine is unchangeable) by its contact with the Iron, only the Iron is changed to become like the Heat, that is to say, hot.
But the Iron will not or ever can it remain hot by itself, it must be in contact with the heat source, with the Flame, to share its principles
of heat. We are not changed into Divine when we experience God, but we are deified in the same sense that the iron is heated without itself necessarily becoming the Flame.
Is this the root of the difference?
1.A. Apparently, the Eastern Orthodox Church believes Christ has two natures, and that the two natures remain two natures even after they are united in the person of Christ.
1.B. The Eastern Orthodox Church also either allows or accepts Miaphysitism, which says he has one nature after the union of the two natures.
2.A. I read in George Florovsky's "The Reaction in Jerusalem" that the OO leader Dioscorus defended himself at Chalcedon by saying that Dioscorus' "Robber Council" of Ephesus “Flavian was rightly condemned because he stillmaintained two natures after the union. I can prove from Athanasius,Gregory, and Cyril that after the union we ought rather to speak only of oneincarnate nature of the Logos."
2.B. The Oriental Orthodox Church adheres to Miaphysitism, which says he has one nature after the union of the two natures.
Does the Oriental Orthodox Church allow for the idea that Christ still has two natures after they are united in Christ's person?
To illustrate how I picture the EO view:
Well, if it were only as simplistic as your concise synopsis explains, unfortunately there are more complex, sociopolitical, theological, historical, and linguistic factors which muddy up such clear thinking between the jurisdictions. I would say that it is incorrect however to say that the EO "either allows or accepts Miaphysitism" because if such were the case, then anathemas aside we would be in reunion.
Oriental Miaphysitism in theological practice seems to be different than EO interpretations, especially in the context of post-Palamas EO theology, and these are where misunderstandings continue between us regarding our mutual differences. Further, we only speak of "two" conceptually, not in practice. We in OO think of Christ as existing in One (mia) Nature, One (mia) Person, having One (mia) Will and Operation. We only think about His humanity to try to understand some of the human things He performs as the Son of Man, and yet we fully adhere to the Union, which abolishes "two" and exists as "one" which has been the crux of the debate for all these centuries.
This of course, fully agrees with Chalcedon II
but does not consider the difference of those natures, of which he is composed, to be only in the onlooker's mind, a difference which is not compromised by the union (for he is one from both and the two exist through the one) but uses the plurality to suggest that each nature is possessed separately and has a subsistence of its own: let him be anathema.
and yet, this Council contradicts itself in next anathema which was drafter confusingly just to spite the Orientals and in the process conflicts with the above quote which speaks of the difference as "only being in the onlooker's mind"
If anyone confesses a belief that a union has been made out of the two natures divinity and humanity, or speaks about the one nature of God the Word made flesh, but does not understand these things according to what the fathers have taught, namely that from the divine and human natures a union was made according to subsistence, and that one Christ was formed, and from these expressions tries to introduce one nature or substance made of the deity and human flesh of Christ: let him be anathema.
We disagree with this because the illustrious Christological Father, Saint Cyril, explicitly states in his formula of the "One Incarnate Nature of God the Word." The crux of the Oriental debate is that we confess "one (mia) nature" and "one person" but we still conceive of the natural Union and the inherent preservation of the faculties of both humanity and Divinity, however in the ontological sense (i.e., concrete reality of the hypostatic Union) there can only be said to be One, whether Person or Nature, because the Subsistence/Hypostasis/Person/Body is mutually interdependent upon the underlying Nature, be it the complexity of Jesus Christ or the simplicity of an inanimate object like a chair, nature and person must coincide as one, naturally and essentially. If there is a separate nature, the hypostatic manifestation is subsequently affected. This is why our OO fathers accuse Chalcedon of Nestorianism, because they explain that there can only actually be one inherent nature of any given Hypostatic form, and that two natures would subsequently have to necessarily exist in two separate Hypostases. We do not abolish or absorb or confuse any of the faculties of the humanity and divinity, however can by our theological language only confess Christ as One Nature, One Person, One Will and Operation, after the duality was abolished in the Union of the Incarnation.
However, as even the Chalcedon II canon suggests, we in OO theological thinking, still on our mind's eye think of the two Natures in distinction, just not function. We believe these function in the synergy of the Union, but still in dialogue we have been less antagonistic in our rhetoric, and even accept the terms "two" in discussion. Getting OO to even concede to use the term "two" has been a miracle of ecumenism enough on its own, I would argue that the ball has been in the EO's court for some time now, and since the 1950s the OO have continued to lead the way in dialogue towards reunion. I pray for the full unity of the One, Holy, Catholic, Apostolic Church, to be one as our Lord Jesus Christ is One.