By Stylianos Gerasimos
Saint Gregory the Theologian, addressing the Apollinarian teaching, opposed it with a Christological teaching within the Tradition of the Church.
Saint Gregory clearly stresses in his letter to the Presbyter Cledonius: "I never have and never can honor anything above the Nicene Faith, that of the Holy Fathers who met there to destroy the Arian heresy; but am, and by God's help ever will be, of that faith; completing in detail that which was incompletely said by them concerning the Holy Spirit; for that question had not then been mooted, namely, that we are to believe that the Father, Son, and Holy Spirit are of one Godhead, thus confessing the Spirit also to be God."
Therefore, the center of the Christology of Saint Gregory, we could say, is the Creed of Nicaea regarding the consubstantiality of the Son with the Father. Saint Gregory stresses the real union of the two natures, the divine and human, in the person of Christ. When the Son and Word of God was incarnated, He received the entire human nature for the salvation of the human race.
"For we do not sever the Man from the Godhead, but we lay down as a dogma the Unity and Identity of Person, Who of old was not Man but God, and the Only Son before all ages, unmingled with body or anything corporeal; but Who in these last days has assumed Manhood also for our salvation; passible in His Flesh, impassible in His Godhead; circumscript in the body, uncircumscript in the Spirit; at once earthly and heavenly, tangible and intangible, comprehensible and incomprehensible; that by One and the Same Person, Who was perfect Man and also God, the entire humanity fallen through sin might be created anew."
Gregory goes on to explain: "If anyone does not believe that Holy Mary is the Mother of God, he is severed from the Godhead. If anyone should assert that He passed through the Virgin as through a channel, and was not at once divinely and humanly formed in her (divinely, because without the intervention of a man; humanly, because in accordance with the laws of gestation), he is in like manner godless. If any assert that the Manhood was formed and afterward was clothed with the Godhead, he too is to be condemned. For this were not a Generation of God, but a shirking of generation. If any introduce the notion of Two Sons, one of God the Father, the other of the Mother, and discredits the Unity and Identity, may he lose his part in the adoption promised to those who believe aright. For God and Man are two natures, as also soul and body are; but there are not two Sons or two Gods. For neither in this life are there two manhoods; though Paul speaks in some such language of the inner and outer man. And (if I am to speak concisely) the Savior is made of elements which are distinct from one another (for the invisible is not the same with the visible, nor the timeless with that which is subject to time), yet He is not two Persons. God forbid! For both natures are one by the combination, the Deity being made Man, and the Manhood deified or however one should express it. And I say different Elements, because it is the reverse of what is the case in the Trinity; for There we acknowledge different Persons so as not to confound the persons; but not different Elements, for the Three are One and the same in Godhead."
In confronting the positions of the Apollinarians regarding the incarnation of the Word, Saint Gregory presents a Christology directly related to Soteriology. "If anyone has put his trust in Him as a Man without a human mind, he is really bereft of mind, and quite unworthy of salvation. For that which He has not assumed He has not healed; but that which is united to His Godhead is also saved. If only half Adam fell, then that which Christ assumes and saves may be half also; but if the whole of his nature fell, it must be united to the whole nature of Him that was begotten, and so be saved as a whole."
It should be noted that, because Saint Gregory refers to the union between the divine and human hypostasis in the person of the Word, he uses the terms "μίξις" (mingling), "κράσις" (blending), "σύγκρασις" (blending together) and "συμφυΐα" (unite). With these terms Saint Gregory stresses the real union between the two hypostases in the person of the Word, without meaning the deterioration of each of the two natures. Thus God the Word received human nature and He exalted and deified it. The Son of God now descends to the world as the God-man and offers people the opportunity to become deified. People now have the opportunity to become immortal, because it was done by God the Word.
"The Word of God Himself — Who is before all worlds, the Invisible, the Incomprehensible, the Bodiless, Beginning of Beginning, the Light of Light, the Source of Life and Immortality, the Image of the Archetypal Beauty, the immovable Seal, the unchangeable Image, the Father's Definition and Word, came to His own Image, and took on Himself flesh for the sake of our flesh, and mingled Himself with an intelligent soul for my soul's sake, purifying like by like; and in all points except sin was made man. Conceived by the Virgin, who first in body and soul was purified by the Holy Spirit (for it was needful both that Childbearing should be honored, and that Virginity should receive a higher honor), He came forth then as God with that which He had assumed, One Person in two Natures, Flesh and Spirit, of which the latter deified the former. O new commingling; O strange conjunction; the Self-Existent comes into being, the Uncreated is created, That which cannot be contained is contained, by the intervention of an intellectual soul, mediating between the Deity and the corporality of the flesh. And He Who gives riches becomes poor, for He assumes the poverty of my flesh, that I may assume the richness of His Godhead. He that is full empties Himself, for He empties Himself of His glory for a short while, that I may have a share in His Fullness. What is the riches of His Goodness? What is this mystery that is around me? I had a share in the image; I did not keep it; He partakes of my flesh that He may both save the image and make the flesh immortal" (Oration 38, On Theophany).
Source: Ekklesiastiki Paremvasi, "Ἡ Χριστολογία τοῦ Ἁγίου Γρηγορίου τοῦ Θεολόγου", March 2005. Translated by John Sanidopoulos.