Not a real atheist?

Intra-faith divisions are certainly among the most dangerous elements of religion. Sunnis vs. Shiites. Catholics vs. Protestants. Orthodox Jews vs. secular ones. To outsiders, these factions look at best shortsighted and at worst fundamentally flawed.

I have heard several people who identify themselves as Christians say that because other people who identify themselves as Christians do not believe in such and such, or don’t agree with so and so, or haven’t done whatever, that they are not really Christians, and some even contend that these counterfeit or phony or somehow not qualified “Christians” (with their scare quotes) will burn in hell. Sometimes the differences they cite sound at least theologically significant, sometimes it’s too subtle or esoteric for me to fathom, and sometimes it sounds like they just don’t go to the same particular church.

To me as an outsider this is bizarre and ridiculous. On the news I hear Muslims dismissing other Muslims as “not good Muslims,” or “not true Muslims” for disparities only they can comprehend. How can theists of any flavor ever hope to attract outsiders when so many differences are cited as disqualifying all the others but their specific variety of religion, differences that seem indistinguishable to anyone not already inside their camp? From the eyes of the uninitiated, their micro-controversies discredit them all as a whole.

That's from Richard Wade at the Friendly Athiest. The question, Wade asks, is whether this is happening to non-theists amid the push for evangelical atheism.

We have several terms that non-god-believing folks use to identify themselves to emphasize other aspects they feel are important. Is there a looking down the nose from those using one term toward those using another? Do humanists look askance at freethinkers? Do skeptics roll their eyes about brights?

Has anyone ever been accused of not being a true atheist by another person calling himself or herself an atheist?