I am an atheist and I understand the desire to have a place to go to weekly to nurture bonds and form camaraderie with like minded people. More people are leaving religion than ever before and I think it's only a matter of time until we start seeing these "mega churches" for atheists more often.
For the first time in history, a significant number of Americans describe themselves as not-affiliated to any major religion. Atheism is clearly on the rise. There will logically be a rise in congregations and assemblies of like minded atheists in the coming years. America's demographics are changing in the 21st century, and atheism is becoming mainstream.