Somehow, I believe at least at one stage of his/her life, the God question must pop up in a person's mind, even when one is comfortable with one's religion.
This book is a great start to know what great minds of the past and present, from Plato to Dawkins, observed about God. I have to say the author has managed to present the big ideas in an easy to follow manner that it doesn't seem like one is reading philosophical stuffs at all.
I'd recommend this book for the curious minds. It is really food for thoughts.