I think that pretty well sums it up, at least in English, Ed. (In Esperanto it can also refer to a determined advocate of Esperanto and its grammar as contained in the 16 Rules of the , as officially adopted by the 1905 World Congress of Esperanto. And believe me, some Esperanto fundamentistoj can be just as bigoted and irrational as some Christian and Muslim "fundamentalists". Though to my knowledge they haven't gotten into car bombs yet. )
I haven't seen any evidence that Breivik is a fundamentalist in any particular doctrinal sense, nor that he has any great interest in the Bible. He seems to be Christian mainly because (a) he's Norwegian and (b) it's the un-Islamic thing to be.