At first glance, one thing that atheism clearly seems to have going for it is this: it doesn’t have any holy books with violence advocating passages in it. Indeed, it doesn’t have any holy books at all.
So score one for atheism?
Not so fast. It is true that under stress or times of war, atheists don’t have a sacred book to pull from the shelf that might justify violent actions. And it is also true that there are obscene passages in the religious books well adapted to times of war (and for a multitude of other situations as well). Religions are, in general, highly adaptive. No doubt. But I’d like you to consider this: Atheism is highly adaptive too. Atheists also have a tradition—the secular tradition—and in times of stress, atheists also reach for ideas, and my question is, “What ideas do they reach for?”
I would suggest that, in times of power struggles or war, an atheist might well turn to Nietzsche, or pull Machiavelli’s The Prince from the shelf, not as sacred texts, but as guides for action, and the intellectual justifying of actions. An atheist soldier in Afghanistan, for example, might well get quite cynical and start reading Joseph Conrad’s Heart of Darkness (with Kurtz’s dark admonition near the end of the novella to “Kill them all”). Atheism, in other words, may not treat Nietzsche or Machiavelli or Conrad as holy writ, but atheism does not exist in a vacuum. Like religious ideas, secular ideas are sought out in different contexts. Like any religionist, an atheist turns to different secular texts for different life occasions (from marriage to war).
I’m suggesting that atheism is no more or less prone to violence than religion—and that violence advocating secular books, in stressful situations, are just as easily brought from the shelf and used for violent justifications as religious ones. You don’t need holy books to find justifications for violence, you just need to pull down Sam Harris, Hegel, Marx, or Darwin from the shelf and read them in a certain way. My thesis is that a world without religion wouldn’t be any less violent or ethically horrifying than a world with religion. It would be about the same.