I’m not surprised you had “some reservations” regarding my comments at the Common Word conference last week. You will understand, of course, that in the concluding section of the paper I was deliberately pushing past the dogmatic limits of the Christian tradition in order to underscore the difference between what I called a “planimetric” theology and a “three-dimensional” and “spherical” metaphysics. I think when you actually read the paper, rather than simply relying on a single hearing, my aims will be clearer, though perhaps no more acceptable to exoterists! I hope to have the talk, “Disagreeing to Agree”, posted with my other articles and papers on cutsinger.net within the next two or three weeks.
To answer your specific question, however, we needn’t turn to metaphysics per se, for in this case my remarks were quite within the mainstream of traditional Christian theology. The line you’ve singled out for criticism, far from being (as you mistakenly suppose) my own formulation, was a direct quotation from the “Athanasian Creed”, or Quicunque Vult. I realize, of course, that the eastern Church has never been as amenable as the West to this statement of faith, in part because it fails to honor the primacy of God the Father within the Trinity. Nevertheless, I don’t think any Orthodox Christian would, or should, dispute the way in which this Creed expresses the hypostatic union of the two natures in Christ.
If you are unfamiliar with it, the Creed can be found here.
As you can see, I was quoting line 35, which explains that the unity of God and man in the Person of Christ came about “not by the conversion of the Godhead into flesh, but by the taking [or assumption] of the manhood into God”. And of course, as I said in my talk, the reason for putting things this way is to safeguard the impassibility of the Divine. Keep in mind that the Bible speaks, for the most part, not sub specie aeternitatis, but within a temporal frame of reference, treating God as if He were an actor in a cosmic drama. For this reason the Incarnation is described, as in Philippians 2:5-12 and the other passages you cite, as if it involved an alteration in God. And yet, as your Catholic Saint Thomas Aquinas and a host of other theologians would insist, He who is actus purus, “pure act”, never begins and never stops doing whatever He does, for His Being is an Eternal Doing, if one may put it this way.
Occasionally, the Scriptures themselves include certain openings or pointers toward this trans-temporal dimension. With regard to the Incarnation, I’m thinking for example of John 3:13, where Christ informs the no doubt baffled Nicodemus that “no man has ascended into Heaven but He who descended from Heaven, even the Son of Man, who is in Heaven.” In other words, no one goes up except the One who came down, and even though this One seems to be speaking to you right now and right here on this earth, He’s actually still there! This is the Bible’s way of making one of the points I underscored in the lecture: God has always been man, and man God.
The “taking up” or “assumption” of humanity should not, however, be confused—as I fear you have—with the heresy of adoptionism, which was rejected by the Church, though not formally so, well before the eighth century synod and council you mention. The adoptionist—or “dynamic monarchianist”, to use the technical terminology—claims that Jesus was simply a man, who was empowered by God to work miracles and who, as a matter of honor, can be called God’s (adopted) son. By contrast, the passage quoted from the Athanasian Creed in no way disputes, but rather confirms, orthodox Christology, for in this case Christ’s hypostatic or consubstantial divinity is not in question. Indeed, it’s precisely because He does share fully in the Father’s divine nature that the “event” of the Incarnation must be understood as involving change, not in the eternal Son or Word Himself, but in the human nature that was “drawn” into participation in Him.
This is no more than Theology 101—remembering of course that there’s no such thing as a theology without at least some metaphysical basis. Having drawn a rather bold line between planimetry and sphericality, I’ll be the first to admit that, here as elsewhere, traditional Christian teaching depended for its formulation, and depends for its expression, upon the very metaphysics—largely Platonic and Plotinian—which the theologians have so often, and so carelessly, dismissed!