You see, the atheists can't win. The old testament no longer applies, and even though there are verses which state that the mark of the law cannot be touched (Matthew 5:23) there is no meaning or indication of it being the old testament.
There needs to be a decent debate with proof of correct interpretation in order to claim it actually does mean the old testament.
If anything God created morality, so if God does anything "wrong" it is not wrong. What people claim as "attrocities" - we have to trust God knows what he is doing. He is the basis of morality. He does everything because he knows what he is doing, so if he does commit attrocities it is OK because he is the leading authority in morality. He is the Lord.