iconoclast: [17] The original iconoclasts were members of the Eastern Orthodox church in the 8th and 9th centuries AD who were opposed to the use or worship of religious images. In more extreme cases their opposition took the form of smashing icons (the word iconoclast comes via medieval Latin from medieval Greek eikonoklástēs, a compound formed from eikón ‘icon’ and the verb klan ‘break’).
The term subsequently came to be applied to extreme Protestants in England in the 16th and 17th centuries who expressed their disapproval of graven images (and popish practices in general) in similar ways. Its general use for an ‘attacker of orthodoxy’ dates from the early 19th century. [iconoclast etymology, iconoclast origin, 英语词源]
"breaker or destroyer of images," 1590s, from French iconoclaste and directly from Medieval Latin iconoclastes, from Late Greek eikonoklastes, from eikon (genitive eikonos) "image" + klastes "breaker," from klas- past tense stem of klan "to break" (see clastic). Originally those in the Eastern Church in 8c. and 9c. whose mobs of followers destroyed icons and other religious objects on the grounds that they were idols. Applied to 16c.-17c. Protestants in Netherlands who vandalized former Catholic churches on similar grounds. Extended sense of "one who attacks orthodox beliefs or institutions" is first attested 1842.