Certainly not a matter of not coming out. But they won't speak up. I have two friends, a couple of the most intelligent people I know, both of whom are de facto as atheist as I am. If you would ask them point blank if they believe in a deity, they would say they don't. But that is as far as they go, and they are always chiding me about the depth of my own feelings on the subject and about my active involvement with Freedom From Religion Foundation. They see me as a wild-eyed radical when I object, for example, to manger scenes in front of city halls.They say, "Aw, what're you getting all worked up about? They're not hurting anything."  I can't get them to see that religion is a self-perpetuating mind virus. I can't get them to see that there is constant pressure by the would-be theocrats here in the U.S. to run things their way.