Too Long, didn't read.
here's my take: its not a surprise that more people are self-reporting atheist.
Back 100 years ago, not believing in God was pretty much unacceptible. You would be a social outcast. Even during the Cold War, what did we call the Russians? Godless Communists!
So now we are living in a much more open society. The people who go to church only for ceremonies (i.e. Weddings and Funerals, and maybe during Christmas/Easter) aren't really religious to begin with; those same people 100 years ago would have still self-reported "religious," but nowadays since there is less of a stigma, they are probably more inclined to say "meh, I'm not really that religious"








