Ebonmuse of Daylight Atheism, in the middle of a long and clearly reasoned post, has just coined a catch-cry! If "fundamentalism" is dogmatic adherence to a particular set of beliefs, well, "fundamentalist atheists" certainly do dogmatically adhere to what we believe to be true, when we think we have reasonable certainty. Of course, the catch-cry (like many) leaves out a crucial point - "fundamentalist atheists" think we can find truth by observing the world and by reasoning logically (few would disagree) and not much else (many would disagree but they wouldn't agree in their manner of disagreeing...).
That said, those who make accusations of "fundamentalist atheism" do usually make one criticism that strikes me as reasonable. Occasionally, those who speak in favour of atheism do end up giving a picture of theism as something which does only evil. This can give some credence to claims that (some) atheists misrepresent or even demonise religion.
It isn't misrepresentation or demonisation to claim that religion can dull a person's critical thinking skills as a result of stating that certain claims ought not be questioned. It isn't misrepresentation or demonisation to say that religion can dull a person's moral sense in exactly the same way. It certainly isn't misrepresentation or demonisation to categorically and uncompromisingly state one's reasoned belief that there is no God!
However, in making these arguments and giving evidence for them, atheists occasionally do one of two things. Atheists can end up giving a nasty picture of religion because in focusing on religion's evil consequences they do not mention that religion can sometimes inspire people to do good. They are not required to do so! There is no rule which states that, when arguing against something, you are required to point out all the good aspects of whatever it is you argue against as well as the bad ones.
Atheists may, perhaps, also end up making generalisations about the evil of religion which are not true. I'm not sure if they have done so, and I shall leave it to those arguing back to point out such statements, if they have been made.
In either case, those arguing for religion are perfectly entitled to argue that in some situations religion can have very good consequences. There may also be a reasonable argument that some atheists paint an unfairly nasty picture of religion. This is not reason to use the term "fundamentalist". "Fundamentalist" implies dogmatic adherence to a position, regardless of evidence. Atheists, on the other hand, usually adhere to what they perceive to the truth, given the evidence. So let me repeat Ebonmuse's phrase, with scorn for the accusation of fundamentalism and using a deliberate oxymoron: I am a truth fundamentalist.
I am a truth fundamentalist. Whatever the cost.