A lack of belief in God is not a small thing. It's a unifying factor. We've all felt the sting of prejudice and bigotry. There's a lot to talk about and build around that. Some atheists have created "Sunday assemblies," but others revile against that and I am one of them. I don't want anything to do with a service on Sunday. It's not my happy place, but lots of people do want that. An atheist organization is very encouraging and endearing. When a believer wants to get together with other believers, he just has to go to church. For an atheist to get together with another atheist, that's a lot more difficult and challenging. One of the big draws of the convention is that you get to walk into a roomful of several hundred atheists. There is a lot of camaraderie.