Have you heard the joke about the Irishman who asks a stranger whether he's a Catholic or a Protestant? "I'm an atheist," replies the stranger. "Ah," says the Irishman, "but what kind of atheist are you—Catholic or Protestant?"
It seemed a feeble joke to me the first time I heard it maybe 20 years ago, but since then I've come to understand that religion is more than just a set of beliefs about god(s), rules to live by, and hopes (or fears) about our existence beyond death. Religion is also about culture and customs. An excellent example of this can be found in Judaism, which places less emphasis on a "personal god" than does Christianity or Islam, and quite a bit of emphasis on ritual and tradition. And don't forget the food! I have no idea whether ex-Mormons crave dishes like Jell-O salad and "funeral potatoes" after they've left the fold; what little I know of Mormon cuisine suggests that it focuses more on frugality and practicality than taste. But I simply cannot imagine "cultural" or "secular" Jews turning up their noses at Jewish food no matter how little regard they have for Jewish theology.
Even atheists like me have been steeped in religious culture all our lives, so I think I understand what English writer and atheist Philip Pullman means when he describes himself as a "Church of England atheist." Pullman says that he "remember[s] the beautiful prayers from matins or evensong or the Communion service" in the voice of his grandfather, an Anglican clergyman. "We can't abandon these early memories, by which I mean both that it's impossible and that it would be wrong." How true. Eliminating all religious-based terms and practices from our lives would be nearly impossible, like trying to remove every chocolate chip from a chocolate chip cookie, and the result would be pretty boring.