It's worth remembering where this debate came from. Atheists, only recently starting to stand up and be counted in any number, are seeing the people who have been saying the same things that atheists have been saying for centuries (as noted in comment 5, then largely ignored) being told to hush up because they're being noticed for once and that's making trouble. These are frequently also the people who gave your rank-and-file atheist the courage to come out and who provide sympathy when coming out results in the crap it always results in. But hush, because what these other people are doing is really important.
Of course, it is important. But so is being supported and encouraged as an out atheist. So is being able to tell people how religion hurt you or those you love without having to put bows on it. So is being able to tell other people that they have a real choice to get out of abusive religions. So is being able to run for public office. So is being able to keep your job. So is being able to keep your kids.
But hush. And be really nice to the people who are telling you to hush. Be nice to the people who are telling you that you matter less than what they're doing. Be nice to the people who are doing good work but only talk about why people like you are bad. Be nice to the people who might, someday let you eat at the grown-up table if you stay quiet enough at the children's table first (and when there are no more grown-up problems you might interfere with). Hush and trust them, despite the fact that they're calling you the problem.
Yeah, no. Atheists are being aggressive, in part, because they're being told to go back to being passive. They're being argumentative because there's a constant onslaught of messages leveled at them and everyone they have to deal with that becomes the unquestioned social background if they don't. They're being rude because everybody is rude sometimes, and they're not going to be left out if you're not. They're being condescending because you've been told this before in some form, but you can't seem to move past the fact that someone insulted you in order to hear it. [from my comment here]
If you happen to be an atheist whose life is arranged so that it never causes you any problems, rejoice. If you're religious and don't see why atheists should behave that way in our "Christian nation" or a country with a state church, take a deep breath and two steps back from the argument (particularly if you happen to be a middle-class or better white male to boot). If you don't know what all the fuss is about, shut up and listen for a bit. Either way, understand what you're demanding of atheists and figure out why you're placing the burden for good behavior on them.
The Support of New Atheism