a person who attacks established beliefs or institutions
a person who destroys religious images or opposes their veneration
iconoclasm /-klaz(ə)m/ noun
iconoclastic /-ʹklastik/ adj
iconoclastically /-ʹklastikli/ adv
[via late Latin from Greek eikonoklastēs image destroyer, from eikōn (see icon) + klan to break]