“Why do we cross our fingers during turbulence, even the most atheistic among us?” asked Atran when we spoke at his Upper West Side pied-à-terre in January. Atran, who is 55, is an anthropologist at the National Center for Scientific Research in Paris, with joint appointments at the University of Michigan and the John Jay College of Criminal Justice in New York. His research interests include cognitive science and evolutionary biology, and sometimes he presents students with a wooden box that he pretends is an African relic. “If you have negative sentiments toward religion,” he tells them, “the box will destroy whatever you put inside it.” Many of his students say they doubt the existence of God, but in this demonstration they act as if they believe in something. Put your pencil into the magic box, he tells them, and the nonbelievers do so blithely. Put in your driver’s license, he says, and most do, but only after significant hesitation. And when he tells them to put in their hands, few will. If they don’t believe in God, what exactly are they afraid of?