Which is why the Nestorian heresy was so insidious, because it split Jesus into two Persons. As God, Jesus cannot suffer or die, yes but as Man, he can and did. But Jesus is only one Person: the Second Person of the Trinity. That’s why although Jesus died as a man, it is perfectly legitimate to say “God died” because it is a Person who dies, not a nature. As such, as true Man, he can atone for the sins of man, but as God, only he could offer the infinite atonement for sins committed against an infinitely good and just God.
On the other hand, a righteous judge, the sinner must take his blame himself. Is it justly to I do sins and a innocent man suffer for it? I can’t think so.
Because this innocent man willingly bore it; it was not imposed on him. And without God becoming man, we would have been unable to atone for our sins ourselves, no matter how badly we were punished, because no matter what, we are finite creatures, and any sin against an infinitely good and just God has infinite guilt. We could never atone for that. Hence, God, out of nothing but his love for us, took it on himself to offer that atonement, because only God can do so. But he had to do it as a man, for the sins of man.