When Melody Hensley first met Lawrence Krauss, she was a 29-year-old makeup artist at a department store, and he was one of her intellectual idols. She ran an atheist website in her spare time and had just started volunteering for the Center for Inquiry (CFI), a nonprofit group committed to promoting science and reason above faith. She was hoping to build a career in the burgeoning “skeptics” movement, and Krauss was one of its brightest luminaries. At a CFI event in November 2006, Krauss asked Hensley for her card, and later, as she was leaving, asked her if she was...