Atheist churches? Nah. Atheists in churches? Sure.
There’s something not OK with appropriating all of this religious language, imagery and ritual for atheism.
Atheism has no dogmas. There is no rule proscribing atheists from appropriating religious imagery. But I agree with the larger criticism. This will not last. Humans do things through motivation. Without a core mission (hee, hee), these gatherings quickly will wane. Those who try it a few times soon will find they prefer doing other things most Sunday mornings.
I like better Jason Testerman’s idea that an atheist should be open to visiting any nearby Christian church, providing the congregants there an example of someone living without faith, and participating in the other side of that dialogue. I don’t think it will happen much. But it’s always helpful for those on opposite poles of some intellectual divide to see each other face to face. And lest any Christian worry, no church ever has been struck by lightning just because I walk in the doors.