Atheists in America face some measure of discrimination, and we want a way to talk about that discrimination so that it's taken seriously. But our approach thus far is setting us back, and may even be putting us in conflict with identity groups who could and ought to be alongside us in a struggle towards pluralistic understanding.
Dawkins' views on religion are by now extremely well-known, to the point of cultural saturation thanks to the media's fixation with him. But the dogmatic assertions and withering dismissals that made Dawkins a media-darling lend themselves particularly well to the anarchic medium of Twitter, where his unjustifiable claims can shrug off any residual requirement for justification.
There have always been fringes in every group that will kill for their cause, but we rarely extrapolate beyond their group membership to make generalizations based on religion, ideology or color. But if we find out tomorrow that the bomber was a Muslim, then I don't think we can say the same. And that's a problem.