Anyone who spends as much time in bookstores as I do can smell an emerging literary fad. About 10 years ago, it was books about angels. Not to be undone, the rationalists and atheists have launched their own cottage industry of "God doesn't exist" and "He's mean" books — Richard Dawkins, Sam Harris, Christopher Hitchens, among them. We are witnessing the birth of another literary craze — the "Do we really need Israel, anyway?" book. (ENLARGE) Jeffrey K. Salkin of Atlanta is an ordained rabbi and director of Kol Echad, an adult Jewish learning center. He is the author of...