I'm not going to wade into the lameness of bumper-sticker wars, but, as I'm sure nearly everyone is screaming at this point, that's rather the point. The "Darwin fish" evolved* as a response to the ostentatious displays of piety on SUVs around the country. You could put it more charitably, but it seems to me little more than an equivalent display of self-righteousness. But Jonah's lopsided sense of equivalence is only beginning.
I find Darwin fish offensive. First, there's the smugness. The undeniable message: Those Jesus fish people are less evolved, less sophisticated than we Darwin fishers.
As an aside, Goldberg's assertion that the Icthus fish is a "cherished symbol" is fairly ludicrous. It is ancient, and was once used for the purpose he describes, but had gone mostly forgotten before some Christian industry marketing whiz uncovered it and decided it would be a great way for a certain kind of bubble evangelical to purchase their public separation from the rest of the heathens.
Doughload here emits a variation on the common right-wing trope. Sure, our religious nuts are a bit crazy but OMG TEH MOOSLIMS!! would totally kill ya if you said the same unkind things about them. This is the NABA-NABA principle at its finest, but I'd previously underestimated how central it is to the right-wing justification for their warmongering.
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.**
What I'm wondering is if there isn't a way in which the wingnuts view every conflict through a dualist lens. Between any two opposing forces there has to be a "good" side and an "evil" side, and we have to weigh their relative merits with the good guys having all of their faults forgiven and the evildoers punted beyond the realms of empathy and rationality. NABA-NABA doesn't register as a concern, because "less bad" is enough reason to inspire unquestioning enthusiasm.
Pandagon has a similar example: How could you possibly be concerned about patriarchal forces in the Western world when Muslim oppression of women is SO MUCH WORSE! And this is the case in every instance; how could you write even once about such lesser worries when there are worse things in the world?
See also, IOZ, Orcinus.
*Lame, but I couldn't resist it
**Doughy's huffy bravado is just all wet here. In many parts of the United States (if not most), you're far more likely to be harmed in some way for showing contempt for fundamentalist Christianity than Islam. They may not chopping heads off yet, but there are other ways to injure a person's life, liberty and prosperity.