Heinrich Heine once wrote a clever poem titled "Marie Antoinette," in which the ghost of everyone's favorite French queen entertains her guests with "strictest etiquette." The irony of the poem is that neither Antoinette nor her guests realize that their heads are missing. They were all beheaded during the French Revolution, but without their heads, they don't have the brains to acknowledge their headlessness. Islam is currently in a similar situation. Muhammad's empire of faith has managed to thrive in the modern world for one simple reason: Muslims have kept Muhammad's dark past a secret. Indeed, they have gone beyond...