Only if grouping by religious belief has some impact on social order, power relationships, ability to realise one's potential, etc, etc. The truth is more probably that atheism is a luxury of over-educated comparatively wealthy intellectual brats, while religion is the last resort of the poor and the working classes. I would wager that there is even today a significant portion of the "religious" who think of god or go to church for a moment of peace and comfort, to hope for a second for some relief, some higher order, meaning, purpose. They don't dominate much when it comes to atheists (especially the non-gay white male variety, which also happens to be the group that claims to speak for the entire clan -- hence my reference to Hitchens and Dawkins, and you might as well throw in Dennett).
--ravi