Lost me right there, at the start. I don't know what the beliefs of the person writing this are, but anyone, atheist or not, who subscribes to this view has a very poor understanding of the concept of atheism.

Atheism is ONLY a lack of belief in a god or gods. Note that it is not an ANTAGONISM towards the concept of god or religion (different concepts), which is called Anti-theism. Naturally enough, the vast majority of anti-theists are atheists, but not all, and conflating the two is a mistake made both by believers and non-believers. Likewise, no position, moral or amoral, can be taken in the name of atheism, since atheism simply describes a lack of belief, not a positive affirmation of anything. If you wish for a moral structure you have to look elsewhere, humanism is the common place to find the moral structure sans-supernatural beings.

I do in fact appreciate the impulse itself, as a matter of fact. It's clear that religion gives people something, and those who have no belief might have an easier time of it if they have alternative venues that give them everything organized religion gives theists (the art, music, community, chance to come together to do good etc.) without having to pledge allegiance to a deity they don't believe in. However, I think that the belief or lack of belief must be kept utterly separate from such activities. Certainly they should be done without god(s) but they must not be TIED to atheism, that is, you should NEVER imply, in any way, that the only way to participate in these groups or experience the activities, is if you are an atheist or agnostic, that otherwise you won't appreciate it. At the most, I'd accept these places and activities offering a chance to experience god-free practices to people of all faiths or none at all. Of course it's more likely that atheists or agnostics participate, but if you make it exclusionary you're just creating another exclusive tribe.

Replacing one dogma with another sure doesn't sound like the best way to promote free thinking.

On one level, I do understand the urge to congregate, however. Atheists are the orphans of US society., and the separation of church and state is very porous and undependable.
Just recently an atheist soldier was sent home early from his tour in Iraq because of death threats by his fellow soldiers. While our military is being indocctrinated about tolerance for the local population, the powers that be apparently don't bother to address tolerance for some of our own.

That kind of thing can make people angry, angry enough to go to exremes of theri own. Bad mistake, IMO.