That Jesus possessed human nature from eternity past... because that overcomes the objection that if Jesus took human nature into Himself 2000 years ago, then Jesus changed. However, I have come across something that helps me see it differently. We know that Jesus was tempted in all ways as we are, yet we know that God cannot be tempted. We know that Jesus died, yet God is immortal. Jesus' divine nature is essential to Him; we might say that His divine nature is His eternal Self. But I think we can safely say that Jesus' human nature was not essential to Him; for example, Jesus' divine nature is immortal and untemptable, but His human nature could be killed and could be tempted. Jesus' divine nature has always been what makes Him uniquely who He is. When divine Jesus took human nature and human flesh, the human nature became a part of what makes Him who He is, but apart from His divine nature, His human nature could never have existed. This seems to indicate that Jesus' human nature was contingent: its existence depended upon, and could not exist apart from, His eternal divine nature. And the taking into Himself of a contingent element would not constitute a change in Jesus' essential qualities but would only be an addition to Himself of that (very real and substantive) human nature. If this is correct and true, then it would be incorrect to conclude that Jesus possessed His human nature from eternity past. Now, it would seem to me that, just as Jesus chose to take human flesh and human nature, He also chose to live and function in His human flesh and human nature (rather than the fullness of His divine nature) while on earth. He chose to grow in stature, became stronger in spirit and wisdom, and went through (relatively) normal human development (Luke 2:40). He chose to refrain from appearing in multiple places at once. He chose to not engage in omniscience (because humans don't do that); when He was asked when the time of the end would come, He replied that no one but His Father knew the day or the hour. Jesus chose to communicate with the Father in prayer like any human should. He chose to be obedient to the Father and to be led by the Holy Spirit. And when they nailed Jesus to the cross, He could very well have come down off the cross... but He chose to stay on it unto death. By His choice, He humbled Himself such that He refrained from showing His full glory and majesty and power (which probably would have slain everyone) and instead lived in His human nature. It must have been incredibly demeaning, but in His love Jesus was willing to do this for us.
Pardon me chiming in late... Human nature, by definition, is not pre-existent. Therefore it would be erroneous to attribute the humanity of Jesus to God the Son in eternity past. There's a language issue that someone poked at but doesn't seem to have resolved: "Jesus" is the name of the person who is both God and man. Jesus was conceived and born. Before the annunciation, "Jesus" did not exist, only God the Son. God the Son "took on flesh" or "was incarnate"... this is not a change to his being, or essence, which is immutable, being exactly divine. Rather he assumed flesh, as I think Athy's Creed puts it; it's a change to his Person that is external to his essence/being/subsistence. So, to reflect on your last post here, the human nature is not essential to God the Son, but it is essential to Jesus. Does that make sense, or did I just rehash what's already been walked through?
I'm going to call it a confirmation. Thank you! The part about "Jesus" not existing until the Incarnation is an aspect of it that wasn't on my radar. I can see your point. Stalwart did allude to it, but I didn't understand until you put it into words as you did. Whereas Stalwart phrased it as, Jesus was not God before his birth, you turned it around and said God was not Jesus before His birth. That makes more sense to me.
Without wishing any offense, it pains me to state the expression “the human nature is not essential to God the son but is essential to Jesus” goes beyond Nestorius to the extreme Christology of Theodore of Mopsuestia, who explicitly stated that there were two persons, a divine and a human, in a union of will. But at a minimum, some of the langauge you are using, as a matter of fact, is that of the Nestorian party and is non-Chalcedonian. The Chalcedonian definition is that our Lord has a divine nature and a human nature in hypostatic union, so that due to communicatio idiomatum, one cannot speak of Jesus Christ without speaking of the Only Begotten Son and Word of God. I should add it is extremely easy to inadvertantly use Nestorian expressions and I myself have been caught unawares at times, which is why I now tend to lean towards the Cyrillian rathet than Chalcedonian formulary as an added bulwark against Nestorius, which is to say that Our Lord posesses one theandric nature from his human nature and divine nature, to quote the Egyptian form of the Divine Liturgy of St. Basil, without mingling, confusion or alteration. This also gives me some comfort given the sinister person of Ibas lurking in the background at Chalcedon, who later came out as a bona fide Nestorian, and the disagreeable, imperious nature of Archbishop Leo I of Rome, who presumed to dictate the Tome to the council and demand the Eastern bishops accept it without qualification, and the important theological contributions of Severus of Antioch to both the Eastern (Chalcedonian) and Oriental (Cyrillian) Orthodox communions, in defeating apthartodocetism, which in the Eastern church was associated with the sanguinary emperor Justinian, and in the Oriental, with people who would later leave for the actual genuine monophysites, the party of Eutyches, John Philoponus and the Tritheists. However, I do not regard Chalcedonian Christology as an error, but the trick is that one must be ever so careful with language. One divine person, one hypostasis, one uncreated divine essence or nature, one created human nature, hypostatically unified so that any statements uttered about the one nature must be applicable to the other. Whereas if one instead uses the model proposed by St. Ephesus and approved at the Council of Ephesus, one can speak of humanity and divinity in the abstract while only talking about our Lord in a unified sense.
This is alas, apthartodocetist, and precisely the error of Emperor Justinian that was later abandoned.
I had a nice, clear mental picture... and now you've scribbled on it. No, not really. Apthartodocetists believed Jesus' body was always incorruptible. No one in this thread has made such a suggestion. God the Son has always been and will always be God the Son, but isn't it possible that He did not go by the name "Jesus" until the Incarnation? We do not deny the hypostatic union. I think perhaps you are seeing nits to pick, where no nits exist; they might be like "floaters" in the eye of the beholder ("Hey, I see a black speck, what's that?").