I decided to skip to the end of Paul Berman's monster essay and I see he winds up talking about Ayaan Hirsi Ali. She, of course, is every western secularist's favorite Muslim precisely because she's, well, not a Muslim. And, of course, from the point of view of western secularists it would be great if we could just partner up with secularists born in Muslim countries and together quash the menace of radical Islamist terrorism.
The trouble, of course, is that politics is the art of the possible, and history shows that it's frequently not possible to do very much of anything with secularist politics. That's why, for example, seeking arguments against Female Genital Mutilation in the Koran seems like an obviously smart move. In countries where large numbers of people believe FGM is required by Islam, arguments of the form "Islam requires FGM, FGM bad for women, therefore Islam should be abandoned" aren't going to get off the ground. Arguments of the form "FGM is not required by Islam" or, even better, "FGM is condemned by Islam" are, pragmatically speaking, much more useful. But an argument like that is only going to be credible coming from a serious Muslim, probably one whose general beliefs are wildly too culturally conservative for my taste or that of any western feminist.