Atheism is not synonymous with the atheist movement. One can be an atheist and not want to have anything whatsoever to do with the atheist movement. In fact, this appears to be precisely the position held by most atheists. That is, most atheists do not have much of anything to do with the atheist movement.
Those of us who consider ourselves part of the atheist movement know this full well, but it is frequently misunderstood by people outside the movement. For a great example, see this op-ed Kate Blanchard wrote for Reason Dispatches.
Blanchard writes that she cannot bring herself to apply the atheist label to herself (even though it clearly fits). Why?
The major issue for me is an aversion to militant secularism, akin to some people’s aversion to “organized religion.” The new atheism, of the sort that has celebrities, conventions, media outlets, or protest marches, is not simply about doubting the existence of traditional deities. It is more often about intellectual elitism, and sometimes even outright racism toward people whom Christopher Hitchens referred to as “semi-stupefied peasants in desert regions.” Orthodox secularism, it seems, is about feeling superior to those poor, deluded souls who still cling to religion—that weird little psycho-social appendix leftover from some earlier stage in human evolution.