I understand and I admit that you are correct in some instances. However, if I may tear down your sentence just there to make a proof, I think you will find this interesting.
You "figure they learned that in school or in church, not from a broad swath of everyday atheists". Let me play with the words for a moment in context of the rest of the post.
This could just as easily say that you "assume they learned it from...".
Even more to the point this could just as easily be written that you have "judged them to be of little experience with other atheists"
A blind judgement. Which you knew because you clarified intent prior to posting the comment knowing that it would be found insulting if I were a lesser man.
This is the same blind judgement that upset Atheists as a whole. The blind judgement of the existence of a God. Or the blind judgemnt of your life choices. Though you were very political in your approach, you have done the same thing which Theists do. Keep in mind that I was once an Atheist myself. However, I do not dare compare my my experiences to yours in this matter. The are most definitely going to prove different.