proselytizer

/ˈprɑsəlɪtaɪzər/
noun
  1. A person who tries to persuade others to join a religion, political party, or other group.
    • She was a tireless proselytizer for her political party.
    • The university warned the proselytizer to stay off campus.
    • The street corner proselytizer handed out pamphlets to passersby.
  2. A person who strongly promotes a particular belief, cause, or product.
    • He is a well-known proselytizer for sustainable living.
    • As a proselytizer of classical music, she gave free concerts in schools.
    • The company hired a proselytizer to spread the word about its new app.