That will give something fun to do as tengris, Vikings, pagan Slavs etc when they raid neighbours. You should also get piety/prestige for destroying religious artifacts of hostile religions. I think IRL certain Jain sects also were broadly iconoclastic but none are in game.) The historical figures you encounter in Crusader Kings 2 may be enticing candidates for waging battles. No Islamic faiths have the tenet, but perhaps it should be extended to some of the more fundamentalist ones? But there's probably no images of prophets in the dlc, so maybe it doesn't matter. The amount of piety lost, gained, and the amount of opinion gained should all scale with the value of the artifacts and whether or not you're zealous or cynical. Similarly, when I play a 769 ERE start, my initial goal is to lose Zealous so that I can renounce Iconoclasm. In exchange they can destroy them for a big piety injection and increased opinion from same-faith and clergy, and lose opinion with zealous same-religion-different-faith characters Religions with the aniconism tenet should lose piety when they possess religious icons (paintings, statues, swords with religious iconography, etc) in their throne room/inventory. I've thought this since playing iconoclastic byzantium in ck2, but since artifacts and faiths are being upgraded in the game, here's an idea:

Ck2 how to lose zealous