Why would God write the rule that our inherited debt be payable by a ransom of his son's life? Who would write a contract with a ransom sacrifice clause that applied to their own son which could be exercised to relieve the other party's debt if the the contract were broken? 

By the rules the Christian God set up, if Adam broke rule number one, there would be terrible consequences which would apply to his children, and all their following descendants, indefinitely, if not later waved by a special act of a scapegoating his son/self to pay the debt.

If God so loved the world, why make the rules like this in the first place? 