Zealot n. : One who is zealous; one who engages warmly in any cause, and pursues his object with earnestness and ardor; especially, one who is overzealous, or carried away by his zeal; one absorbed in devotion to anything; an enthusiast; a fanatical partisan.

Example:
Can and should a philosopher be a Zealot?

Taxonomy
Zealots, Romans, Zealotry, the Jews, Masada, Sicarii, Rome, Jerusalem, Simon the Zealot, free dictionary, free encyclopedia, Jewish, Josephus, the destruction of Jerusalem, H. H. Ben-Sasson, translations, zelotes, History.

Defination from the web:
Zealot, in Hebrew kanai (קנאי, frequently used in plural form, קנאים), means one who is zealous on behalf of God. ... Two modern translations (Jewish New Testament and Alternate Literal Translation) render it as 'a zealot' ...