If you are unafraid of obscurity and want to stick with something Greco-Latinate that somehow parallels the word whose antonym you seek, then maybe combine *hagiography* with *iconoclasm* to get:

> **hagioclasm**

I have found one and only one precedent, in Michael Knox Berran's *Jefferson's Demons: Portrait of a Restless Mind*:

> He longed to handle the relics, to meditate in the groves, to pray in the shrines sacred to the sainted prophet of the Republicans. But he would do so with the passion that destroys sanctity rather than exalts it, and in a fit of **hagioclastic** zeal he determined to show up his old protector's stigmata for a fraud.

It's that "destroys sanctity [non-ecclesiastically conceived, as in your modern usage of "hagiography"] rather than exalt it" that underlines the meaning...


NB: Further uses: 
[Heroes, Hagiography, and Villany][1] - Tim Challies
[Dark Chaucer: An Assortment][2] by Myra Seaman 
[Broken Idols of the English Reformation][3] by Margaret Aston 


  [1]: https://www.challies.com/articles/heroes-hagiography-and-villainy/
  [2]: https://www.amazon.com/dp/0615701078
  [3]: https://www.amazon.com/dp/0521770181