fanatical

fəˈnatɪk(ə)l

adjective

filled with excessive and single-minded zeal.

fanatical revolutionaries

zealous,extremist,extreme,militant,dogmatic,sectarian,bigoted,rabid,maniacal,radical,diehard,activist,prejudiced,chauvinistic,intolerant,narrow-minded,single-minded,partisan,blinkered,illiberal,inflexible,uncompromising,swivel-eyed