In April 2005, when the Vatican began to seek a successor to John Paul II, technology author Rogers Cadenhead registered the domain names ClementXV.com, InnocentXIV.com, LeoXIV.com, BenedictXVI.com, PaulVII.com, and PiusXIII.com, hoping that the new pope would take one of these names. “Someone else already has JohnPaulIII.com and JohnXXIV.com,” he wrote on his blog, “but otherwise I put a chip down on every name of the past three centuries.” When Joseph Ratzinger chose the name Benedict XVI, “I felt like my horse had come in first at the Kentucky races,” he told CNN. As owner of the new pope’s domain, he...