Church Fathers: Miaphysitism

“As I have said, if we understand the manner of the incarnation we shall see that two natures come together with one another, without confusion or change, in an indivisible union.”
(St. Cyril of Alexandria, First Letter of Cyril to Succensus)
After the union has occurred, however, we do not divide the natures from one another, nor do we sever the one and indivisible into two sons, but we say that there is One Son, and as the holy Fathers have stated: One Incarnate Nature of The Word.”
(St. Cyril of Alexandria, First Letter of Cyril to Succensus)
“As to the manner of the incarnation of the Only Begotten, then theoretically speaking (but only in so far as it appears to the eyes of the soul) we would admit that there are two united natures but only One Christ and Son and Lord, the Word of God made man and made flesh.”
(St. Cyril of Alexandria, First Letter of Cyril to Succensus)
“If we deny that there is one single Christ from two different natures, being indivisible after the union, then the enemies of orthodoxy will ask: ‘If the entirety amounts to one nature then how was he incarnated or what kind of flesh did he make his own?'”
(St. Cyril of Alexandria, First Letter of Cyril to Succensus)
“‘If Emmanuel was composed from two natures,’ they say, ‘and after the union one conceives of only one incarnate nature of the Word, then it necessarily follows that we must admit he suffered in his own nature.’ The blessed Fathers who defined for us the venerable creed of the orthodox faith said that it was the Word of God himself, the Only begotten from God’s own essence, through whom are all things, who became incarnate and was made man. Evidently we would not say that these holy ones were unaware of the fact that the body that was united to the Word was animated by a rational soul, and so, if anyone says that the Word was made flesh he is not thereby confessing that the flesh united to him was devoid of a rational soul.”
(St. Cyril of Alexandria, Second Letter of Cyril to Succensus)
“They also said the following: ‘If there is one incarnate nature of the Word then it absolutely follows that there must have been a mixture and confusion, with the human nature in him being diminished or stolen away as it were.’ Once again those who twist the truth are unaware that in fact there is but one incarnate nature of the Word.
(St. Cyril of Alexandria, Second Letter of Cyril to Succensus)
“So, those who say that ‘if there is one incarnate nature of God the Word, then it necessarily follows that there must have been a mixture or confusion with the human nature being diminished or stolen away,’ are talking rubbish.”
(St. Cyril of Alexandria, Second Letter of Cyril to Succensus)
“I understand that another query has been raised in regard to these matters, as follows: ‘So, anyone who says that the Lord suffered only at the level of the flesh, makes that suffering mindless and involuntary. But if anyone says that he suffered with a rational soul, so that the suffering might be voluntary, then there is nothing to prevent one from saying that he suffered in the nature of the manhood, and if this is the case then how can we deny that the two natures endured after the union? So, even if one says: ‘Christ, therefore, having suffered for us in the flesh’ (1 Pet.4.1), this is no different from saying: ‘Christ having suffered for us in our nature.’ This objection is yet another attack on those who say that there is one incarnate nature of the Son. They want to show that the idea is foolish and so they keep on arguing at every turn that two natures endured.”
(St. Cyril of Alexandria, Second Letter of Cyril to Succensus)
“…we divide them only at a theoretical level, and by subtle speculation, or rather we accept the distinction only in our mental intuitions, and we do not set the natures apart nor do we grant that they have a radical separateness, but we understand them to belong to one man. This is why the two are no longer two, but through both of them the one living creature is rendered complete.”
(St. Cyril of Alexandria, Second Letter of Cyril to Succensus)
“We say that there is one Son, and that he has one nature even when he is considered as having assumed flesh endowed with a rational soul.”
(St. Cyril of Alexandria, On the Unity of Christ, pg. 77)