The strongest counter argument comes from, e.g., Mackie, viz., God could have created free beings who never choose to sin. I think Alvin Plantinga has done the best job of answering that. By arguing this way, you show the atheists are right.
Atheists are right only in pointing out the existence of evil.
With that theists agree. Abraham had the divine perspective. He trusted God. God had promised him that through Isaac would come a great nation. Therfore, Abraham reasoned, even after sacrificing Isaac, God would bring him back from the dead.