Atheists, why do you claim Christianity is illogical?

Is it logical to believe that GOD SACRIFICED, TORTURED AND KILLED his own saintly Son ? How can anybody believe such a lie about God ? That is pure calumny. God is too good to do anything like that. He won't even punish or condemn the Sinners, why would He do that to a saintly, pure and innocent man like Jesus ? I find that simply unbelievable.