First off, by fundamentalists' I don't mean people who blow themselves or others up, burn down government buildings because of cartoons or threaten workers in clinics, and by right I don't mean they're right to believe it (EDIT: or do it).
Ok, so what do mean? By fundamentalist I mean someone who believes in the fundamentals of something and by right I mean their view is right.
I should probably also point out as a disclaimer that I am an atheist, possibly even a militant atheist if such a thing is possible and the situation is appropriate.
Unnecessary waffling aside, and the point still waiting to be broached Id better get on with it.
There seems to me to be 2 basic types of religious person: those who believe that their chosen deities written word is only a guide to life and pick and choose what to take literally, what to consider outdated and what to believe happened as written; and the other, the kind that believe word for word what is written down on behalf of their god is their gods words, no argument, no discussion.
Now, if you are going to believe in a God, and to me believing in a God seems a pretty major thing as I have never had the slightest inclination to believe in one and would need some convincing, aren't you better off believing that what you believe to be their book is indeed their book and following that to the letter? Not revising what you choose to accept as the truth and picking what you like and discarding what you don't?
In typical religious simplification and comparison - take football (or soccer for those in the US): If you play football but remove or alter a rule because you don't like it, are you really playing football, or simply playing your own version of a ball game?