Have you seen how many "orgainzed" atheist sites there are now, where people of the same cause are coming together to push their cause? I see many athiests as not only non theists but actually taking offense to the idea which creats a polarity effect and certainly then satisfies the 4th aspect of the definition I supplied.
Sometimes I think terms have many meanings and connotations and depending on conditioning, etc one can be offended or not care to much about any or all definitions anyway, which I think is a good thing. Look at how some christians argue that their brand of christianity is the only right one. Labels divide humanity. That much I do know. ALl ways for the ego to thrive in a way such as a drop in the ocean believes it is the ocean. Look at me I'm the one....I'm special.....my way is important....I must be identified this way, not that way......*EGO Dance* filtered through chritians, jews, athiests, realists, newagers, etc! Same energy wrapped up in differing belief systems.