Therefore He Who is the Shepherd of the whole rational creation, left in the heights of heaven His unsinning and supramundane flock, and, moved by love, went after the sheep which had gone astray, even our human nature.
For human nature, which alone, according to the similitude in the parable, through vice roamed away from the hundred of rational beings, is, if it be compared with the whole, but an insignificant and infinitesimal part.
It was impossible that our life, which had been estranged from God, should of itself return to the high and heavenly place.
Therefore, as St Paul says, He Who knew no sin is made sin for us, and frees us from the curse by taking on Him our curse as His own.
And, having taken up and…“slain” in Himself “the enmity” which by means of sin had come between us and God—(in fact sin was “the enmity”)—and having become what we were, He through Himself again united humanity to God.
For having by purity brought into closest relationship with the Father of our nature that new man which is created after God, in Whom dwelt all the fulness of the Godhead bodily, He drew with Him into the same grace all the nature that partakes of His body and is akin to Him.
And these glad tidings He proclaims through the woman, not to those disciples only, but also to all who up to the present day become disciples of the Word
—the tidings, namely, that man is no longer outlawed, nor cast out of the kingdom of God, but is once more a son, once more in the station assigned to him by his God, inasmuch as along with the first-fruits of humanity the lump also is hallowed.
“For behold,” He says, “I and the children whom God hath given Me.”
He Who for our sakes was partaker of flesh and blood has recovered you, and brought you back to the place whence ye strayed away, becoming mere flesh and blood by your sin.
And so He from Whom we were formerly alienated by our revolt has become our Father and our God.
Gregory of Nyssa (c 335 – after 394): Against Eunomius, 12,1.