It’s a matter of life and death to Ali, who has needed protection since Theo van Gogh—her collaborator on a documentary about the repression of women under Islam—was murdered in 2004. Reached in Paris last week, Ali said she was “deeply grateful” to Harris and others who have come to her defense. (The cost of her protection is secret, but it’s believed to exceed $2 million a year.) She’s working on a new book, “Shortcut to Enlightenment,” in which the Prophet Muhammad comes back to tour New York City and debate modern (although dead) philosophers John Stuart Mill and Friedrich von Hayek—not a subject likely to calm Islamist anger. She awaits the day, she says, “when there are no longer people who believe they can get to heaven by killing me”—or when her dissent from Islam has gathered enough adherents “that it won’t pay to kill one or two of us.” Until then, says Harris, those who believe in freedom of thought have an obligation to try to keep her alive.