quibbling over insignificant details; "caviling pettifoggers and quiggling pleaders"-Edmund Burke; "her nagging and carping attack"; "thought her editor unnecessarily nitpicking"; "a pettifogging lawyer's mind"; "had no patience with quibbling critics"
a person motivated by irrational enthusiasm (as for a cause); "A fanatic is one who can't change his mind and won't change the subject"--Winston Churchill
marked by excessive enthusiasm for and intense devotion to a cause or idea; "rabid isolationist"