Douthat disputes that claim by first deconstructing the ethical reduction of the Christian Gospel.
... Suppose we put the question like this: Imagine that conclusive archaeological and textual evidence emerged to prove that the whole story of the birth, life, and death of Jesus of Nazareth was either a delusion or a fabrication? Suppose the mother had admitted shyly that, in fact, she had fallen pregnant for predictable reasons? Suppose we found the post-Calvary body?Serious Christians, of the sort I have been debating lately, would have no choice but to consider such news as absolutely calamitous. The light of the world would have gone out; the hope of humanity would have been extinguished.... If all the official stories of monotheism, from Moses to Mormonism, were to be utterly and finally discredited, we would be exactly where we are now. All the agonizing questions that we face, from the idea of the good life and our duties to each other to the concept of justice and the enigma of existence itself, would be just as difficult and also just as fascinating.
The Christian story is not, for instance, a theological or philosophical treatise. It's not a set of commands or insights about our moral duties. Nor is it a road map to the good life. It has implications for all of those questions, obviously; certainly, Jesus of Nazareth wasn't exactly silent on "the concept of justice" during his lifetime, and Christians have been deriving theologies, philosophies and codes of conduct from his example ever since. But fundamentally, the Christian story is evidence for a particular idea about the universe: It recounts a series of events that, if real, tells us something profound about the nature of God, and His relationship to His creatures, that we couldn't have been expected to understand or accept in precisely the same way without the Gospel narratives.Douthat argues convincingly that atheists couldn't pose the question in quite the same way before the claim of the Incarnation. What kind of demand could we make on such a distant God?
Consider, for instance, the way in which the dominance of the Christian story has actually sharpened one of the best arrows in the anti-theist's quiver. In Western society, especially, the oft-heard claim that the world is too cruel a place for a good omnipotence to have created derives a great deal of its power, whether implicitly or explicitly, from the person of Christ himself. The God of the New Testament seems more immediate, more personal, and more invested in his creation than He had heretofore revealed Himself to be. But this arguably makes Him seem more culpable for the world's suffering as well. Paradoxically, the God who addresses Job out of the whirlwind is far less vulnerable to complaints about the world's injustice than the God who suffers on the Cross - or the human God who cries in the manger. For many Christians, Christ's suffering provides a partial answer to the problem of theodicy. But for many atheists and agnostics, it only sharpens the question: How can a God who loves mankind enough to die for us allow us to suffer as much as we do?Whether or not this argument would convince Hitchens, it is a common fallacy to discount the social and historical influences on our thinking. Once in grad school, a fellow student absurdly claimed that if she had lived in the 16th century, she would have been a harlot, because she would not have been able to accept the constraints on women then.
For a glimpse of pre-Christian life, the miniseries Rome is enlightening, if we can't glean it from certain societies in our world today. We can fall back that far again, but it can never be as hopeless as before.