When I tell people that I'm an atheist, I'm often asked if I think that fiery rhetoric and sharp critiques of religion, like the kind found in the writing of trailblazers like Richard Dawkins, is harming the cause by offending believers who might otherwise have been sympathetic. The implication is that, if we focus our attacks only on the worst fundamentalists, we'll gain public support and approval, but if we criticize faith in general, we'll never get anywhere.
I don't believe this is true, and to explain why, I usually invoke the concept of the Overton window. This is an idea first conceived by the political scientist (who else) Joseph Overton, which holds that, for any political issue, there's a range of socially acceptable positions that's narrower than the range of possible positions. Positions within the Overton window are seen as mainstream and uncontroversial, while those outside it are viewed as shocking, upsetting, and dangerously radical. The key point is that, with social pressure, the Overton window can shift over time, and today's radicals may be tomorrow's moderates.
For example, just a few decades ago, the idea of same-sex marriage was all but impossible to even conceive of. But a few people did conceive of it, and dared to advocate it. At first they were only a handful of radicals, but over time, the idea gained support. Now, it's an established right in states and countries around the world, and is slowly but steadily moving into the mainstream. Even President Obama says he supports civil unions, if not true marriage equality - in many ways a disappointing compromise, but it's a sign of how much the Overton window has shifted in only a few decades that even this half-measure could be openly advocated by the elected leader of the country. (This also shows why politicians are almost never the drivers of real change. Most successful politicians try to find the Overton window and plop down in the middle of it, which means they inevitably get left behind when it shifts in one direction or another.)
All social reform movements have to shift the Overton window to make progress. The concept of different races mingling in public, or women voting, or animals having rights - all these are examples of issues where the Overton window has moved over time, so that positions which were once viewed as unthinkably radical have become the accepted wisdom, while those that were once considered mainstream are now outside the window, and unacceptable to advocate in mixed company.
So, how do you shift the Overton window? The answer is simple: You have to stand outside it and pull. Social change always begins with a few brave people who dare to advocate something previously unthinkable. And most of those first-generation advocates, to be perfectly honest, suffer scorn, ridicule and opprobrium, are often even targets of persecution and violence. But by their mere existence, by their willingness to stand fast on their principles and refusal to compromise, they stretch the boundaries of what the majority considers possible and redefine what counts as the "moderate" position.
With this metaphor in mind, we can more clearly see what the atheism debate is all about. The moderates and accommodationists giving us advice - what they're really asking is to leave the Overton window where it is, for us to target only the people whom wider society already agrees are wrong. The New Atheists, meanwhile, have a different goal in mind: we believe that as long as religious faith is the accepted and unquestioned default, atheism will never be socially acceptable. By criticizing all faith, we want to shift the Overton window in our direction and make atheism more familiar, more accepted, and therefore more influential. In the long run, that will win us more converts and allies than a strategy of just being nice.