Strange the mentality of religious believers who refer to atheism as a "religion". It is akin to the same people who refer to evolutionary theory as "Darwinism" and who talk about a "belief" in evolution, and evolution as religion (but more of that another day).
So why is it so? Well, because the religious believers cannot conceive of people who have no religious belief. If atheism itself is a religion then that is understandable -- after all they accept that there are a number of religions (although only one of them, their own, is actually true). They think indeed that the proposition that all humans believe is a validation of their own religious beliefs. But if they understood that atheists simply don't believe then this might throw into doubt their whole basis for belief. Rather in the way that Chavez and Castro have to be rejected because capitalism is the only possible economic belief.
But more, if they fully understood that atheism means "no god(s)" then the belief in a particular god or gods stands exposed as a willfully blind acceptance of a set of beliefs for which there is no evidence. Why, in a world chock full of facts, would you choose to base your life on something which is fact free?
And the charge is a sign of the effectiveness of Dawkins and Dennett, Harris and Horton, in combating the unfounded belief system that is religion. If we atheists just have a different belief system, if atheism is a "religion" (merely to write the phrase shows the absurdity), then, as the schoolyard chant goes, "You're an idiot", "You are and you don't know you are, so there".
So atheism is a religion? No, I'm afraid not, no more than being completely healthy is just another kind of disease. But believing it is so must be a comfort in a foxhole, or in the cold hours of doubt at 3am. And the evangelicals would rather vote for someone with the screwy set of beliefs that is Mormonism (can Tom Cruise, seeing Mitt's success, be far from a political career?) than for an atheist.
Like Shelley, the Watermelon Blog believes "The great instrument of moral good is the imagination; and poetry administers to the effect by acting on the cause".