Let us know what the author of this book says about this. Sounds interesting.
I'm about 50 pages in now. He seems to say that we should not "throw the baby out with the bathwater," that while he doesn't believe in God he nonetheless acknowledges that some people do and that this belief makes a positive impact on them. He does not believe that morals are derived from God or religion, but that religion has often played a central role in teaching people morals, and that regardless of whether you are an atheist or theist that spirituality has a role to play. Community is a big thing for him, and he sees it as more important than specific beliefs, even about God (though he acknowledges that many have the opposite approach). He spends about 10 pages trying to drive this point home. One of his many examples/points was about a story (or maybe it was a joke) about two Jewish guys who stay up all night debating whether God existed. They finally decided that God did not exist, and then went to bed. The next morning one of the guys woke up and found the other guy praying, and asked him what he was doing, and hadn't they decided that God didn't exist? The guy who was praying said of his prayers: "What does God have to do with it?" Comte-Sponville put this in the context of other religious stories/ideas, trying to build up the idea that ethics, community, etc. are necessary for civilization, regardless of what you think about the God question.
He also thinks the idea of the sacred to be important; not that something is sacred because of a connection with the divine, but in the sense of it being set apart or set higher, and there being a duty or obligation involved. He considers extremes on both sides, religious fundamentalism and atheistic nihilism, to be dangers to be avoided. He doesn't seem to care much for Nietzsche, or at least while he admires his eloquence he dislikes his conclusions. I don't find a lot of his arguments to be particularly persuasive, though he is at least a good deal more civil than others writing about the same topics. He hasn't really got to a lot about what role spirituality plays, or what it would even look like, for an atheist. About a third of the book seems to be dedicated to spirituality in particular, but that's not till the end (Part 3 is titled: "Can There Be An Atheist Spirituality?")