As Christopher Caldwell once observed in the Weekly Standard, Darwin fish flout the agreed-on etiquette of identity politics. "Namely: It's acceptable to assert identity and abhorrent to attack it. A plaque with ŒShalom' written inside a Star of David would hardly attract notice; a plaque with ŒUsury' written inside the same symbol would be an outrage."

But it's the false bravado of the Darwin fish that grates the most. Like so much other Christian-baiting in American popular culture, sporting your Darwin fish is a way to speak truth to power on the cheap, to show courage without consequence.

Whatever the faults of "Fitna," it ain't no Darwin fish.

Wilders' film could easily get him killed. It picks up the work of Dutch filmmaker Theo van Gogh, who was murdered in 2004 by a jihadi for criticizing Islam.

"Fitna" is provocative, but it has good reason to provoke. A cancer of violence, bigotry and cruelty is metastasizing within the Islamic world.

It's fine for Muslim moderates to say they aren't part of the cancer; and that some have, in response to the film, is a positive sign. But more often, diagnosing or even observing this cancer - in film, book or cartoon - is dubbed "intolerant," while calls for violence, censorship and even murder are treated as understandable, if regrettable, expressions of anger.

It's not that secular progressives support Muslim religious fanatics, it's that they reserve their passion and scorn for religious Christians who are neither fanatical nor violent.

The Darwin fish ostensibly symbolizes the superiority of progressive-minded science over backward-looking faith. I think this is a false juxtaposition, but I would have a lot more respect for the folks who believe it if they aimed their brave contempt for religion at those who might behead them for it.