I’m very happy to engage with you on this, my friend. I’ve been a Bible-believing Christian for 35 years, and can assure you that the moral standard of the God of the Bible is far higher than that of anyone on the earth, including your good self.
As I understand it, your problem is that in order to deal with the problem of sin God sent Jesus to suffer on the cross, shed His blood, and die; and you see this as being in violation of the highest principle of morality, which is to care for others, especially children, and to keep them from harm.
Before we get to the Bible let’s ask ourselves a question: is it ever morally acceptable to do harm to another person, or to put them into a position where harm might befall them?
I attended a health and safety briefing where the consultant (whom I’ll call Jim for convenience) told this story. Jim had been a sailor, and one day there was an accident and the clothes of one of his colleagues caught fire. The man was rushing about like a headless chicken, panic-stricken. Jim took a pole and struck the man across the shins. This got him on to the ground, where they were able to cover him with a blanket and smother the flames. Unfortunately both his legs were broken. Was Jim’s act of breaking the man’s legs immoral?
There was a case recently in England where three burglars broke into a house, and the householder shot and injured two of them with a legally-held shot-gun. Was his act immoral? The judge said no; he was quite within his rights to protect his family and his property.
Last year, American forces found Osama Bin Laden in a compound in Pakistan and killed him. Was their act immoral?
My parents lived through a world war, when young men from Britain and America were sent out in order to halt the abomination that was Hitler’s Third Reich. Was it an immoral act to send these men out to face the horrors of war and almost certain death?
Is it morally acceptable to do harm to someone in order to prevent greater harm being done either to themselves or to someone else? The obvious answer is “yes”.
Now, God sent Jesus to be crucified in order to save you and me from eternal punishment in hell. Was that an immoral act? One person suffered for a limited time to prevent multitudes from suffering for an unlimited time. That is not an immoral act. That is an act of mercy.
You say that it is immoral to punish the innocent instead of the guilty, even if the innocent one is willing to take the punishment. Actually, the God of the Bible would agree with you in most cases. There are two examples in the Bible of men being willing to bear eternal punishment in order that the people of Israel might be saved – Moses (Exodus 32:31-33) and Paul (Romans 9:1-5). However, the only person that God would allow to suffer and die, not only for Israel but for all mankind, was Jesus, because He was the only one who could possibly survive such an ordeal.
You say that God’s first principle of morality is care/harm. Actually God’s first principle is love – "you shall love the Lord your God with all your heart, mind, and strength, and you shall love your neighbour as yourself". Read Luke 10:25-37 to understand what Jesus means by that.