I still think as an atheist that the Bible can be appreciated as a work of literature, morality tales, and is open to literary criticism. I always preferred the somewhat esoteric Jewish interpretation which saw this episode as a failure of Abraham, not a positive story about his faith. God never talks directly to him again following the whole Issac debacle. This interpretation sees Abraham's lack of objection, especially when he earlier challenges God over the destruction of Sodom and Gomorrah ("will you destroy the city if you can find 50 righteous men? 40 righteous men? 30? etc..."). God wanted to be challenged; God wanted Abraham to do as Socrates does and ask constantly, especially against authority, what is the good? What is moral? What is just? Abraham didn't do that here so the story is about the supreme failure of Abraham and not his triumph by blind faith. In fact I was reading somewhere that this may be a more original interpretation (for whatever that's worth) than supposed. There is some evidence that the text showing approval given by God (after the angel stops Abraham) for Abraham's blind faith is actually a later insertion by another author. Just some interesting trivia.

Edit: Just in case it's unclear, I place stories like this on equal footing with the Upanishads, The Quran, Greek myths, etc.. in terms of metaphysical truth. I just happen to think the above retelling is much more compelling and interesting.

From: http://www.stltoday.com/lifestyles/faith-and-values/civil-religion/hyim-shafner/did-abraham-fail-the-ultimate-test/article_d5ebdeae-1090-11e1-9012-0019bb30f31a.html

"I would like to suggest perhaps a new explanation. I am led to this possibility by the abundance of questions the story leaves us with and the dearth of satisfying answers. Perhaps the real test was for Abraham was to confront God as he did at Sodom, thus teaching his children “righteousness and justice,” and ultimately to say “no” to God. Perhaps, on some level in this narrative, Abraham failed the test. I would suggest this is why God never speaks to Abraham again after the binding of Isaac. In the end of the story an emissary angel speaks to Abraham - but where is God? Why doesn’t God just speak directly to Abraham? Perhaps Abraham’s leadership and God’s relationship with Abraham has ended. Perhaps if we begin to see this narrative as a test in which the right answer is to protect an innocent child rather than sacrifice him in obedience to God, our world, one in which millions of religious people trace themselves theologically back to this story, might be a bit less violent."