Zealotism is a noun that describes excessive enthusiasm and passion towards a particular cause, often religious or political in nature. Synonyms for zealotism include fanatical devotion, extremism, radicalism, fervor, fanaticism, dogmatism, and obsession. These words all suggest a strong commitment and unwavering conviction to a particular belief or ideology. However, they also imply a potential danger or negative connotation of being too extreme or unyielding in one's views. Other related words to zealotism include fervency, intense commitment, single-mindedness, and ardent dedication, which all denote a strong passion and devotion towards a cause but do not carry the same negative connotations.