There is nothing difficult in this, the only way Jesus could bear our sin was by being of the same nature as us, by being of that same nature that was subject to sin, yet without sinning. If He did not have the same nature as us, He could not have been in a position to bear the sin that we sin. All sorts of silly arguments centre around the sinless nature of Christ, His perfection and sinlessness, of being the spotless lamb.
So we were tempted and we sinned, Jesus was tempted but did not sin. How hard can it be? It is similar to those who say the law continues for us, when the statement plainly is that WE ARE NOT UNDER THE LAW. [yes, we are OVER it]. We having lost our identity through the accusation by the law of us sinning, not having the power of any moral authority behind us, did sin. Jesus knew who He was, the Son of God, and having all the moral authority under the sun behind [above] Him, and in Him, did not sin.
But it was when Jesus allowed Himself to enter into that same nature of ours which contained the possibilities of sin and to sin, that matters became more confused. We have to acknowledge that all sin comes through the thought processes of our brain, of our thinking. That if we arrange certain thought patterns in certain ways, we may end up with a structure that is ungodly. And that if our bodies have certain desires which tend to favour the self rather than others, then we may become self-serving instead of other serving or God serving.
So if the reason for these self serving desires can be sorted out and eliminated, then a completely new scenario is created. The righteous Spirit of Jesus entered into these physiological areas of physicality and of mentality and did battle with them. The righteousness He had become was able to confront and overcome all these areas of service to the self, similar to when temptation led Him to avoid food for forty days in denial of His body, and to refuse to take upon Himself the kingdoms of this world as His prize, because He knew He was in charge of all those kingdoms already, and also the kingdom of heaven.
So He defeated within Himself, not only those thought patterns set up within the human makeup necessary for our survival, he also altered the physical, psychological, and complete physiology of the human form, so as to destroy the very root cause of sin, that of the temptation itself. While this was in progress we hear Him cry “My God, My God, Why have you forsaken me”. The battle was hard and the darkness of evil was felt within Him as the struggle continued in His body, now dealing with the reality of inner sin, just as Paul said “evil is present in me, the one who wishes to do good”. Well Paul could NOT do the good, but Jesus fought until all the deficiencies that were of the natural human birth had been overcome and replaced by all the elements of the Spiritual birth, leaving no remnant of that human nature left by which it might resist or oppose God at all. “It is finished” He cried.
His body was now rendered as immortal, but death had to ‘seal the deal’ to set the scene for resurrection. HE ‘gave up’ His spirit of His life OF the flesh from which He had entered IN (into) the flesh, and then died. He literally became sin for us, He became the object of “the wrath of God” as the righteousness of God that He was, was brought to bear on the unrighteousness of elements of His “flesh”, His body, in which lay those miserable components of self generation and self preservation, until Holiness pervaded every part of Him, and not just in His Spirit. He became the completed perfected creature of creation that God seeks also for us, which is why the ‘hope of the Christian” is not stated to be heaven going or any such thing, but is the RESURRECTION OF THE BODY, of the WHOLE person, of the NEW CREATION in Christ, yet to be revealed by the fire of purification on the last day, but intended to be seen in THIS life as by faith people apprehend the message of complete redemption done for them at great cost, His life, His body, His blood, His immense SUFFERING for us.
[The question arises as to the nature of guilt that He bore for us, within Himself. The nature of the case suggests that He bore the pain and the suffering of the guilt for which we are guilty, no guilt of His own. And how could there be any of His own, He had done no wrong. Yet it must have been HIS conscience that was under attack, perhaps as being the god-head representative it was to do with the assumption of the responsibility for having created a wayward creation which produced so much evil. LOVE that suffers the consequence of loving enough to bring into existence the children of that love, yet then suffering the consequence of love unreturned, and the ultimate loss of those His children. Yet the internal darkness would be completely recognisable in terms of gaining that victory over those thought patterns of guilt, in terms of depression, anxiety and the absolute stress of having to justify the whole process within the body of His Son, as Love did its necessary work within Him.]