I know a few that stay from the family.

I would however say that a lack of religiosity is not quite the same as being atheist, or even agnostic. I personally know several people that only go for the big holidays Christmas, Easter so on but are most certainly not atheist, we have had this same conversation and was informed that they believe in God, end of story.

My best friends, that helped me when I left religion will not call them self's atheist even though they dislike everything about it... There is just a emotional link that people have a hard time breaking sometimes.

@MichaelSpinler mentioned the Clergy Project. It's a big deal for many professional religious people to remain anonymous. I heard from someone who helps run it that some have been outed, which devastated their lives forever. A co-founder, Daniel Dennett, studied 5 such people; the study is linked to here: [clergyproject.org]

not as many who say there religious but do nothing about it apart from saying they are religious.

I think most people are actually pretty skeptical when it comes down to it. Otherwise people wouldn't be so frightened of death.

My guess is there are a lot more than most people realize. There could be any number of reasons that atheists might keep their belief (or lack thereof) to themselves. Family considerations, social stigma, business considerations, lack of desire to discuss/debate, etc.

I sometimes wonder if my father was one of these individuals. He never openly admitted to being atheist, but only rarely went to church and, on the rare occasion he did, always sat in the rear. He explained it away as, "I sit in the rear in case I have to go to the rest room." It also occurred to me from time to time that he was "going through the motions" more than anything else when it came to saying grace at the table, and he didn't seem surprised or upset when I came out as atheist. It may also partially explain the distance between he and my mother, who slept separately since I can remember. They both died years ago, though, so I cannot ask them.

I can understand why he might have been this way, though. As far as I know, I am the only atheist in my extended family -- the "black sheep," so to speak. The remainder of my extended family are quite religious, including several who are ordained ministers or otherwise deeply involved in their respective churches. I do have one cousin who I think might be atheist, but he is not open about it so I do not know for certain. I do not hide my atheism and I believe it is the cause of the rift between myself and my three siblings, as my sisters and I rarely speak despite the fact that they speak among themselves regularly.

I'm suspecting it's a huge unrecognized / subterranean phenomenon. In fact my brother is one who clearly doesn't believe, hasn't darkened the door of a church in at least twenty years, and who will privately admit his unbelief to me and to me only. But not even really to himself enough to follow through on the implications and "come out". And at his age (71) I don't know that there's any real point. His Catholic wife isn't observant so he's not being made to "live a lie". It's just a matter of indifference.

It's easy to imagine him kicking it up a notch or two and actually going to church. Indeed if he and his wife were a little more social, they might well do that, for the only things churches are actually good for (sometimes): community and refuge.

In fact this overt atheist and his unbelieving wife have been toying with that ourselves. We're in our early 60s and trying to establish friendships / common cause is difficult for introverts like us. We've considered two very inclusive liberal churches, one Episcopalian and one Unitarian / Universalist. The latter is a post-Christian denomination that openly accepts atheists as well as theists, but it's a little too political and cliquish for our taste. And a bit too white and elitist -- we like diversity despite being WASPs ourselves. The Episcopalian church addresses those issues but we frankly can't stand the 90-minute liturgical extravaganza that they call a church service. And to really "belong" we'd have to BS our way in and go through a lot of motions since this is NOT a post-Christian situation. My wife enjoys volunteering at the food kitchen they run though.

I think both experiments may end up as failures, but it illustrates that there can be unbelievers in the midst of churches.