What Sort of Human Nature Did Jesus Have?

The doctrine of the Incarnation declares that the eternal Son of God, in adding humanity to his divinity, became Jesus Christ—one person with two natures; fully God and fully human. Reflecting on that truth, many ask, What sort of human nature did Jesus have? Some say it was the one possessed by Adam and Eve before the fall. Others say it was human nature corrupted by the fall.

Though GCI does not consider this issue to be a core doctrine, it does (in alignment with historically orthodox Christian doctrine) teach that our salvation as humans is directly and fundamentally related to Jesus being human on our behalf in every respect. By uniting human nature with his perfect and perfecting divine nature, the Son of God brought to humanity the regeneration and healing we so desperately need yet are unable to achieve for ourselves. This means that Jesus not only took upon himself our sinful external condition but also our human nature, corrupted by the fall. This understanding clarifies the doctrine of the Incarnation and points to the profound depths of Christ’s atoning work on our behalf.

Gregory
A notable theologian of the early church in the East who taught that the Son of God assumed corrupt human nature was Gregory Nazianzen (AD 329-390), one of the Cappadocian Fathers. In his First Letter to Cledonius, Gregory wrote this:
If anyone has put his trust in Christ as a Man without a human mind, he himself 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 of 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 who was begotten, and so be saved as a whole. (quoted by Thomas F. Torrance in The Christian Frame of Mind, p. 9, emphasis added)
[Note: for an earlier Surprising God series exploring the book, The Christian Frame of Mind, click here.]

Iranaeus
Gregory's assertion that the unassumed is the unredeemed had been put forward earlier by Irenaeus (died ca. AD 202). From early on (particularly in the East) the church taught that in the Incarnation
...the holy Son of God assumed from the Virgin Mary our fallen human nature, with all its weaknesses, sin and guilt, yet in such a way that instead of sinning himself he brought the judgment of God to bear upon us in the depths of our human nature, redeeming, healing and sanctifying at the same time what he took from us, through his atoning birth, life, death and resurrection. (The Christian Frame of Mind, p. 9)
T.F. Torrance
Thomas F. Torrance is one of several trinitarian theologians in our day who, following Irenaeus, Gregory, Athanasius and other theologians of the ancient eastern church, teach that the Son of God assumed corrupt human nature—what the apostle Paul calls our flesh:
For God has done what the law, weakened by the flesh, could not do: by sending his own Son in the likeness of sinful flesh, and to deal with sin, he condemned sin in the flesh, so that the just requirement of the law might be fulfilled in us, who walk not according to the flesh but according to the Spirit. (Rom. 8:3-4, NRSV) 
Torrance asserted that there is no reason (biblically and theologically) to hold back from affirming that Jesus, during his earthly life, bore what he called “defiled” or “depraved” human nature—the nature that so desperately needs Christ’s atoning and redeeming work in order for it to be healed and converted back to God. Torrance explains:
Through his incarnation, the Son of God has made himself one with us as we are, and indeed made himself what we are, thereby not only making our nature his own but taking on himself our lost condition subject to condemnation and death, all in order that he might substitute himself in our place, discharge our debt, and offer himself in atoning sacrifice to God on our behalf. Since sin and its judgment have affected the actual nature of death as we experience it, Christ has made our death and fate his own, thereby taking on himself the penalty due to all in death, destroying the power of sin and its stronghold in death, and thus redeeming or rescuing us from its dominion. (The Trinitarian Faith, p. 157)
Additional explanation from Torrance concerning this teaching is found in the book Incarnation: The Person and Life of Christ. Here is a representative quotation:
Are we to think of this flesh which he became as our flesh? Are we to think of it as describing some neutral human nature and existence, or as describing our actual human nature and existence in the bondage and estrangement of humanity fallen from God and under the divine judgment? It was certainly into a state of enmity that the Word penetrated in becoming flesh, into darkness and blindness, that is, into the situation where light and darkness are in conflict and where his own receive him not. 
There can be no doubt that the New Testament speaks of the flesh of Jesus as the concrete form of our human nature marked by Adam's fall, the human nature which seen from the cross is at enmity with God and needs to be reconciled to God. In becoming flesh the Word penetrated into hostile territory, into our human alienation and estrangement with God.... 
Now when we listen to the witness of Holy Scripture… we know we are faced with something we can never fully understand, but it is something that we must seek to understand as far as we can. One thing should be abundantly clear, that if Jesus Christ did not assume our fallen flesh, our fallen humanity, then our fallen humanity is untouched by his work—for “the unassumed is the unredeemed,” as Gregory Nazianzen put it. Patristic theology, especially as we see it expounded in the great Athanasius, makes a great deal of the fact that he who knew no sin became sin for us [quoting 2 Cor. 5:21], exchanging his riches for our poverty [quoting 2 Cor. 8:9], his perfection for our imperfection, his incorruption for our corruption, his eternal life for our mortality [alluding to 1 Cor. 15:53]. Thus Christ took from Mary a corruptible and mortal body in order that he might take our sin, judge and condemn it in the flesh, and so assume our human nature as we have it in the fallen world that he might heal, sanctify and redeem it. In that teaching the Greek fathers were closely following the New Testament. If the Word of God did not actually come where we are, and join himself to us and range himself with us where we are in sin and under judgement, how could it be said that Christ really took our place, took our cause upon himself in order to redeem us? What could we then have to do with him? We stand before God as flesh of sin under God's judgement, and it is into this concrete form of our sin-laden, corruptible and mortal humanity in which we are damned and lost that Christ came, without ceasing to be the holy Son of God. He entered into complete solidarity with us in our sinful existence in order to save us, without becoming himself a sinner. (Incarnation, pp. 61, 62)
Not all theologians (ancient and contemporary) agree with this understanding that the Son of God assumed corrupt human nature. In fact, most theologians after the 5th century in the West took a different view. Torrance explains why:
Western divergence from the eastern Church can be traced back to [Roman Catholic Pope] Leo [ca. AD 440] rejecting the eastern teaching that in the Incarnation the Son of God took our depraved human nature upon himself… [Leo] held instead that it was not our fallen Adamic nature but some neutral human nature in Christ that became the instrument for his saving work for mankind. The theological consequences of that position were immense, as we can see in the typical approach of Latin theology to the idea of original sin as in the teaching of St. Augustine, in its formulation of a doctrine of atonement, largely in terms of external juridical relations, and… in the Roman [Catholic] dogmas of "the immaculate conception" and the "assumption of Mary…." Failure to recognize that the human mind, far from being neutral, is actually estranged and twisted, and thus in need of internal healing, opened the door to a pre-Christian Greek rationalism that has affected not only western theology but all western culture. (The Christian Frame of Mind, pp. 9, 10)
Most contemporary objections to the teaching of the eastern church on this topic arise out of presuming that the assumption of our human fallen condition would necessarily cause Jesus to sin, thus making him a sinner like we are. But that logic is based on an unwarranted inference—one that is not necessarily true. We understand from Holy Scripture that Jesus, in the midst of his incarnate life, never ceased having a divine nature. Jesus’ human nature never existed apart from his divine nature—at all times he remained one with the Father and the Holy Spirit. That relationship makes all the difference as to why Jesus, the eternal Son of God, never sinned as we do. The author of Hebrews repudiates any false inferences to the contrary by asserting that Jesus was indeed “like us in every respect,” being “tempted… as we are,” yet “without sin” (Heb. 2:17; 4:15). Though the Son of God assumed our fallen human nature, rather than being tarnished by it, it was sanctified by his touch. Torrance put it this way:
[Christ’s assumption] of our flesh of sin was a sinless action, which means that Jesus does not do in the flesh of sin what we do, namely, sin, but it also means that by remaining holy and sinless in our flesh, he condemned sin in the flesh he assumed and judged it by his very sinlessness. (Incarnation, p. 63)
This understanding is consistent with the biblical teaching that Jesus’ life was one of sanctifying himself (John 17:19, ESV). There would have been no need or even possibility of this being the case if Jesus had an unfallen (uncorrupt) human nature. We also note in Scripture that Jesus learned obedience, even though he was the perfect Son of God (Heb. 5:8). The human nature our Lord assumed was regenerated (remade or reborn) in Jesus by means of all that he went through during his life on earth, culminating in his crucifixion and ascension. Then, what Jesus achieved in his divine-human person is shared, by the indwelling Holy Spirit, with all who put their trust in Jesus as their Lord and Savior (Titus 3:5-6). This is why the apostle Paul writes in 1 Corinthians 1:30 (NASB) that Jesus, who is our life, is our “sanctification.”

The good news is that the eternal Son of God, the Word, in becoming human via the Incarnation, assumed the human nature that is just like ours. In possessing that nature and resisting its downward pull at all points throughout his life, Jesus restored, renewed and so perfected that nature. Never succumbing to corrupt human nature, he never once sinned. Thus, there is no aspect of human existence, no depth of our fallen nature, that the redeeming work of Jesus has not touched and thus healed. Torrance comments:
From his birth to his death and resurrection on our behalf [Jesus] sanctified what he assumed through his own self-consecration as incarnate Son to the Father, and in sanctifying it brought the divine judgment to bear directly upon our human nature both in the holy life he lived and in the holy death he died in atoning and reconciling sacrifice before God. That was a vicarious activity which was brought to its triumphant fulfilment and which received the verdict of the Father’s complete approval in the resurrection of Jesus as God’s beloved Son from the dead and in the rebirth of humanity in him. (The Mediation of Christ, p. 50-51)
Through what Jesus did throughout his life on earth, bearing all the while our corrupt human nature, a reconciling exchange took place, as noted by the apostle Paul:
For our sake he [God] made him [Jesus] to be sin who knew no sin, so that in him we might become the righteousness of God. (2 Cor. 5:21)
The eternal Son took upon himself our corrupt (fallen) nature and purified and healed it through his life of perfect obedience to the Father. According to Torrance,
The work of atoning salvation does not take place outside of Christ, as something external to him, but takes place within him, within the incarnate constitution of his Person, as Mediator. (The Trinitarian Faith, p. 155) 
Now in heaven, Jesus, who remains both fully God and fully (now glorified) human, shares his perfected humanity with us by the Holy Spirit. Though we continue to bear corrupt human nature, we are being conformed more and more to Jesus’ perfected humanity until that glorious day when we will be granted, via glorification in the resurrection, the fulness of perfected humanity. It is by Jesus' vicarious (representative, substitutionary) humanity, united to his divinity, that we are justified, sanctified and glorified. Hallelujah!