Question: How could God punish His innocent Son for the guilt of man?
The doctrine of the Bible is not that God, a holy first person, takes the sins of man, a guilty second person, and lays them upon His own holy Son, an innocent third person. That is the way the doctrine is often misrepresented. In fact, it is the depiction usually made by those who reject the Bible doctrine of substitution - that Christ, as our Substitute, suffered and died for our sins in our place.
The real teaching of the Bible is that Jesus Christ is NOT a third person, but that He is indeed the first person - "that God was in Christ reconciling the world to Himself" (2 Corinthians 5:19). In the atoning death of His Son, instead of laying the punishment of guilty man upon an innocent third person, God took the shame and suffering due to man upon HIMSELF. That is the complete opposite of being unjust and cruel - it is amazing grace!
Furthermore, Jesus Christ was also the second person. He was not merely a man, He was the Son of Man, the representative Man, the Head of the race. No ordinary man could bear the guilt of other men, but the Son of Man, the representative Man, could.
If we take the teaching of the Bible as a complete whole and not in a fragmentary way, it is the most wonderful philosophy the world has ever known. We will ponder and admire its inexhaustible depths throughout eternity. But if we take any one doctrine out of the Bible, the other doctrines become absurd. If we give up the doctrine of the deity of Jesus Christ, then the doctrine of the Atonement becomes an absurdity, and the difficulty suggested by this question naturally arises. Or if we give up the doctrine of the real humanity of Christ, the doctrine of the Atonement loses its profound significance. But if we take all that the Bible says, namely, that Jesus was really divine, "God ... manifested in the flesh" (1 Timothy 3:16), and that He was truly a man, not merely a man but the Son of Man, the representative Man, then the doctrine of the Atonement does not present any difficulties. Rather, it presents an amazing depth of truth.
It is strange how little the average objector to the doctrine of substitution knows about the real doctrine of the Bible on this point. Instead of fighting what the Bible really teaches, he is fighting a figment of his own uninstructed imagination.
~R. A. Torry~