Atheists turning to cult behaviour?

[Mister Agenda]

While that's technically correct, reality is not like that - there is such a thing as the atheist community offline and online which is comprised of activists, writers and speakers, they do conferences together, there are official orgs, have blogs, networks. At the same time, the public perceives atheists as a group with leading proponents which are almost household names. Again, technically, pure atheism may have no other consequences, but that's not a useful insight here imho

It's probably worth noting here that although many atheists in America are involved in organized activites of special interest to secularists and people interested in the company of folks unlikely to treat them like they have three eyes if they know you don't believe in God; the vast majority of atheists in America are not involved in such activities. There are several million atheists in the USA. American Atheists and the FFRF however, have less than 24,000 members between them. Add in all the Facebook and Meetup groups and Sunday Assemblies, and if you account for multiple memberships, I expect it's much less than ten times the membership of AA and FFRF. The American Humanist Association, whom the OP would place in the 'not acting like organized religion category', on the other hand, is probably upwards of 35,000 members all by itself.