The Church Fathers who formulated the creeds were adamant in insisting that God the Son assumed a sinful human nature in the incarnation. To them, the incarnation itself exploded any so called separation of divinity and impurity. Against the Nestorian heresy, the Church in the year 451 came down squarely on Biblical testimony that Jesus Christ is two natures but one person. The one person aspect is in critical view here, because it keeps us from saying Christ’s divine nature and sinful nature were just two hermetically sealed natures pasted together. Nestorianism was an effort to protect the purity of the divine nature of Christ by separating it out from the human nature. Instead of saying “the human nature of Christ became sin,” or “the human nature of Christ died,” we can say with more orthodox correctness that God became sin, and God died. We must recognize that when we say Jesus Christ is 100% God and 100% man, we do not mean that he is made up of two 100%’s glued together; we mean that he is wholly a man “like us in every way” and at the same time wholly God. “Amazing Love, how can it be, that Thou, my God, wouldst die for me?”
1. The Bible tells us that Jesus in his humanity was without sin. Period.
Hebrews 4:15 For we do not have a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sin.Hebrews 7:26 For it was indeed fitting that we should have such a high priest, holy, innocent, unstained, separated from sinners, and exalted above the heavens.1 Peter 2:22 He committed no sin, neither was deceit found in his mouth
Romans 8:3 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 for sin, he condemned sin in the flesh,
The Bible could not be clearly, Jesus became like us in every way with respect to our humanity (i.e. our human nature) but was always entirely unlike us with respect to sinfulness. Jesus assumes are humanity in order to redeem it, but as Athanasius points this does not entail the assumption of our corruption that plagues humanity after the fall of Adam.
Therefore, following the holy fathers, we all with one accord teach men to acknowledge one and the same Son, our Lord Jesus Christ, at once complete in Godhead and complete in manhood, truly God and truly man, consisting also of a reasonable soul and body; of one substance with the Father as regards his Godhead, and at the same time of one substance with us as regards his manhood; like us in all respects, apart from sin;...
However, there is, according to orthodoxy no mixture of the natures. We have no mixing of the Godness of the Son and the humanity of the Son. They are united in the person but this union is:
without confusion, without change, without division, without separation; the distinction of natures being in no way annulled by the union, but rather the characteristics of each nature being preserved and coming together to form one person and subsistence, not as parted or separated into two persons, but one and the same Son and Only-begotten God the Word, Lord Jesus Christ. (Chalcedonian Creed)
We need to be clear what we mean by 'two natures'. The Anathemas of the Second Council of Constantinople speak clearly of the two natures along with what we mean by their union:
a difference of the natures of which the ineffable union took place without confusion, a union in which neither the nature of the Word has changed into that of the flesh, nor that of the flesh into that of the Word (for each remained what it was by nature, even when the union by hypostasis had taken place);
The Godiness of the Son does not cease. It is not restricted, bound, or lessened. While the Word becomes flesh, the divine nature of the Word remains divine. In his deity, the Son retains omnipresence. The finite cannot contain the infinite. Yet the person of the Son of God becomes like in all things (yet without sin). He becomes truly human. 1 John tells us that God has come in the flesh--that to touch Jesus Christ was to touch the person of God (obviously God the Son not God the Father). John's gospel tells us that no one has seen God the Father, but 'the only God' (i.e. God the Son) has made Him known.
The mystery of the incarnation is the God the Son would dwell in our midst becoming like us in all things, bearing the guilt of our sin, and being a high priest for us.
Fuzzy thinking about the incarnation leads to fuzzy thing about a whole mess of topics. We disrespect the Son of God if we speak of Him bearing our sinful nature in the incarnation. We deny the continued deity of Christ if we see deity and humanity mixing in a way that either (a) creates a third category or (b) confusses deity and humanity. The deity and humanity are forever in the incarnation distinct yet inseparable. The hypostatic union is indeed a mystery that my God would die for me!