Okay, on a science site you are stopping me right there and saying, "Isn't atheism just about believing on one less God than 90% of the world? And what's with all this social engineering business?"
It's an intentional fracture in skepticism and atheism and humanism, it seems. As Per Smith puts it at irritually.org, it is ironically downright sectarian. And apparently quite exclusive. Not exclusive in the sense that an American Express Centurion is exclusive (you have to be dumb enough to pay $2,500 a year or whatever it costs now) but in the sense that they want to show everyone how much more awesome they are than cultural barbarians (outsiders), namely by ridiculing and stereotyping everyone who is not the right kind of feminist. Don't think a guy asking you for a coffee is rape? Maybe you are the wrong kind of feminist, Richard Dawkins.
The downside to trying to create an umbrella for lots and lots of people with some aggressive beliefs, as skepticism has tried to do, is that eventually the militants will turn on you too.
For an outsider like me, watching the dynamic unfold is interesting even if I don't get the need for the drama. They seem to agonize over leadership - because it looks too much like a church, which clearly has a leader - and that means they are reacting to what they think people will think people will think before they think it. Not very rational. All religion has to do to kill any formal atheism that becomes powerful enough to get any cultural attention is call the person the most dangerous 'the leader' and the rest will turn on them. As he replies in a comment, how can they even decide who is in the Atheism + group if no one is going to set a standard and everyone will agree on something so simultaneously inclusive and exclusive and therefore fuzzy it is arbitrary, along the lines of 'this person is a friend of mine, can we let her in?'
I'm no expert in this, plenty of people inside will tell me my perceptions are all wrong, I just linked to it because Smith wrote an interesting piece on a subject I know little (and care less) about - it takes some skill to make an irrelevant topic (in science, anyway) like who is hating who in skepticism, atheism or all of the other -isms people create while they insist they are not anything like religion, interesting to outsiders. They do share one -ism; fundamentalism.
And fundamentalism is important if you are going to create ideological purity in your movement. That word 'purity' is an important one. But since I am not fawning over the bloggers who want to remake the world in their image, I have to worry I will get burned in their holy fire.
Read the article by Per Smith but you should probably comment there rather than here. He, and his audience, are in touch with the interpersonal complexities of all this and no one on Science 2.0 is.