I don't get the point of this tread. You can fill in any word in the "fundamentalist" definition and achieve the same effect. I could say that "An honest person is characterized by a rigid adherence to the principle of truth-telling and is often intolerant of lying". It basically takes any person who believes anything and slaps them with an inappropriate label.
Religious fundamentalists are different from people who follow other principles (like scientists with evidence based methods) in that their principles are without evidence. Therefore, there are not up for discussion. You could ask a scientist why they do experiments, or utilize mathematical models, or put their ideas up for peer review. They would explain that these methods are successful, they *actually work*. One can look at the evidence. Similarly, a person who believes in human rights could explain to someone else that they "believe" in their humanitarian principles by showing them how their work improves people's lives.
A religious fundamentalist has an opinion, and he might have some ancient scriptures, but that's not a rational argument. Also, the intolerance factor is important. Scientists may criticize creationists, astrologers, and "natural" healers, but they don't go around killing them in the streets or blowing up their businesses. Contrast this with religious fundamentalists who will sometimes fly planes into buildings or shoot abortion doctors because they think God said it was OK. The distinction is pretty clear.