> If you mean fundamentalism in the strict sense of rigid adherence to a core principle, religious fundamentalists act as they do because the core they follow,

> If you mean fundamentalism in the strict sense of rigid adherence to a core principle, religious fundamentalists act as they do because the core they follow, scripture I don't like the way many people use the term "fundamentalism". It started out to describe an early 20th century movement in American Protestantism. And indeed, they were all about following scripture–or at least what they claimed it was saying, since other Christians have always disagreed with their interpretations of it. And I don't have a problem with calling them "Fundamentalists", since that is their own term they chose to describe themselves. Nor do I have a problem using the term to describe (ultra-)conservative Protestants who consciously continue the same approach today, and look back on the early 20th century Fundamentalists in admiration. The problem is when the term "fundamentalism" gets extended to (ultra-)conservative factions within other religions such as Catholicism, Islam, Judaism, etc. None of those belief systems shares the Protestant belief in "Scripture Alone" (sola scriptura). All three believe in the binding nature of extra-scriptural/post-scriptural traditions. So while "the core they follow, scripture" is an accurate description of the basis of the original Protestant fundamentalism, it ends up misrepresenting "fundamentalism" in other religions, and distorting them through a Protestant-coloured lens. Which is why a lot of scholars of religion object to using the term "fundamentalist", and instead advocate using customised terminology for each religious tradition. Hence people speak of "Islamism" or "jihadist Salafism" or "Khomeinism" rather than "Islamic fundamentalism", for example. Instead of "Catholic fundamentalism", people speak of "Feeneyism" or "radical traditionalism" or "integralism" or so on. Instead of "Jewish fundamentalism", we have terms like "Kahanism". Instead of "Hindu fundamentalism", "Hindutva". And I know by trying to talk about a "core principle", maybe you are acknowledging that for "non-Protestant fundamentalism", the core might not be "scripture". But, just because Protestant Fundamentalists might be said to have a single core principle, doesn't mean every other religion does. Sometimes there is no single core principle, just an assortment of views. People use "fundamentalism" to describe religious views which have a rather hostile attitude towards what we might call "modern scientific liberalism", and whether you have a single core principle or an amorphous blur of many principles is irrelevant to whether you have such a hostile attitude or not