Let's definitely not refer to King Diamond as an authority on Biblical studies and history. He's far from educated on the matter.
Despite his error in referring to Cain and Abel, I think what is important here is the implication. This God who demands that Abraham sacrifice his son is the same God that says "Thou shalt not kill." I think it ironic, because this statement is contradicted numerous times in the Bible. Now, there is the argument that of course killing is acceptable in some cases (I personally believe it is too). However, I think the story of God demanding that Abraham sacrifice his son is one of the cruelest I have ever read. In today's world most of us could never imagine doing such a thing, or that God would ask such a thing of us. I believe this is also why most of us feel dissociated with Christianity. However, there are elements of the story that we should reconsider. Today, we would call someone insane who kills their child in the name of God; but we must remember that in the story Abraham was in direct communication with God. God was commanding him to do these things. So of course, he was justified in carrying out this sacrifice, right?
Why is it, I ask, that we're so eager and prepared to believe this story told to us by the Bible, but in today's world if the same event transpired, we would call Abraham insane?