Here are, according tto Roger Olson, the ‘symptoms’ of the spiritual disease called ‘fundamentalism’:
1) A tendency to elevate doctrines historically considered “secondary” (non-essentials) to the status of dogmas such that anyone who questions them questions the gospel itself.
2) A tendency to eschew “Christian fellowship” with fellow evangelical Christians considered doctrinally “impure” along with a tendency to misrepresent them in order to influence others to avoid them.
3) A tendency to “hunt” for “heresies” among fellow evangelical Christians and to reward fellow fundamentalists who “find” and “expose” them—even where said “heresies” are not truly heresies by any major confessional standards shared among evangelical Protestants.
4) A tendency to place doctrinal “truth” above ethics such that misrepresenting others’ views in order to exclude or marginalize them, if not get them fired, is considered justified.
5) A tendency to be obsessed with “liberal theological thinking” that leads to seeing it where it does not exist along with a tendency to be averse to all ambiguity or uncertainty about doctrinal and biblical matters.
(Source, ‘What Is “Fundamentalism?”’)
NOTE: In case you wonder if you are a fundamentalist.