The New Testament does not teach “two natures in one person”, if that means two blobs, joined at the hip. The church used that nomenclature to articulate the implications of the NT, in a process dominated by the Greek static concept “nature”. Those who articulated “two natures in one person” would also hold “without separation, without confusion”, and this is what saved them from an essentialist blind alley.
It is inaccurate to speak of two natures as if they inhabited Jesus side by side, and one slid through Mary as if through a receptacle, except that the other, the human, was grafted onto the divine and out popped a bicameral being. The church rightly rejected that heresy, and its opposite. Any premise resembling this will always end in heretical dualism.
“Quod non assumpsit, non sanavit”…whatever was not assumed, was not saved. His kenosis allowed his divine “nature” to assume all the characteristics of our humanity. There was no thing that happened to the humanity which did also happen to the divinity, and vice versa, IN THE INCARNATION. sO, the divine nature of Christ was born of Mary, as was the human. To say that she was the mother of God is not to diminish God, nor to imply that she added anything to His divinity, nor to to imply that she caused God. She was His mother in His incarnate divinity, not in His pre-incarnate divinity.
Of course, the divinity is not an identity with the humanity; it (He) pre-existed Mary and was unoriginate, but still born of the Theotokos. In so far as He is God: Unoriginate, yet He proceeds from the Father and was born of a virgin — not just as Jesus of Nazareth but also as the 2nd person of the Trinity.
The language of the creeds is always “this, yet that” and this rhythm of thought is always the mark of the mind baptised by orthodoxy. Commentary on the two natures or the triune God which does not preserve this patristic and poetic, careful quality is inevitably rationalistic.
TimothyOne 