This is a bit of a side-topic, but may I respond?
I can't speak for other atheists. But I have called belief in God a mass delusion before on this forum. This is a claim put forward in the spirit of evaluating the merits of the claim, and having a discussion as adults. It is not meant as a put-down. It is not, I can say very honestly and sincerely, intended to elevate myself in some way, as if I am superior because I am the only non-deluded person in the world. Quite the opposite. It would be more like if we were hiking in the woods, and I pointed out that I thought I saw a tick on your back. Maybe I am mistaken, but I still think it's helpful to you to tell you what I *think* I see. And I am sure that in all likelihood, there are ticks on me as well. And I hope you will point out to me any ticks you think you see.
I believed in God. I have very close friends and family who believe in God. It should go without saying that this is not the sort of delusion that an insane person has. It is popular delusion, and we know all of us succumb to such delusions one way or another. There are some people who accept that belief in God is a sort of delusion, but they say that not all delusions are bad. Studies have shown, in fact, that we all need to have somewhat unrealistic views of ourselves, and our own worth, in order to be happy. So clearly some delusions are okay.
That's the spirit in which I say such things, or at least it's the spirit I try to maintain, anyway.