zealot
$ \mathrm{zealot} /ˈzelət/
noun
(often disapproving)
​a person who is extremely enthusiastic about something, especially religion or politics
SYNONYM fanatic
TOPICS War and conflict C2
Word Origin
mid 16th cent. (in the sense ‘member of an ancient Jewish sect’): via ecclesiastical Latin from Greek zēlōtēs, from zēloun ‘be jealous’, from zēlos.