I don't really want to come across as a guy that is trying to "proselytize" or "crusade against the "heresy of "monophysitism,"" but there are still some elements in me trying to understand what happened in Chalcedon with this controversy, that I'm having trouble wrapping my mind around.
And that is the staunch opposition of Dioscorus, and later Severus of Antioch and other Oriental saints, to this phrase, said phrase which was famously in the Chalcedonian Definition.
It seems that these proponents argue that this phrase "en duo physeon" seems to imply in of itself heterodoxy, that perhaps there is really no union of the two natures or that there are two hypostases of Christ.
However, in light of the fact that this specific term was used by Orthodox proponents before - Saint John Cassian and Saint Ambrose for example - and was even accepted as legitimately Orthodox by Saint Cyril in the Reunion of 433, why do Oriental Orthodox feel that this phrase was worthy of schism?
I think Severus argued that although there may be Saints even recent who used the term, the Nestorian controversy gave it a whole new meaning, as the phrase was routinely used by the Nestorians. However, how can this be a legitimate argument, in light of the fact that DURING the Nestorian controversy, Saint Cyril agreed to the idea that it's an acceptable expression of the Faith - as long as there is a recognition that the Natures are united together, while still retaining each others' properties, but inseparable; and a recognition that the Word is fully God and fully man after the Incarnation?