Honestly, if we’re going to use such standards and definitions that a “nonviolent genocide” is possible, then I’m not sure I understand what makes such a thing wrong. In Japan, the number of people who believe in and practice Shinto is in decline, and more and more people are paying for Western style weddings, so temples are struggling to keep their doors open. Is that an inherently bad thing? Is that genocide?

Come on, you can do better than that.

People changing their culture on their own volition is obviously different from people being forced to by those in power.

How about in the context of the Allies pressuring the emperor to renounce his claims to divinity, undermining a major aspect of Shinto beliefs? Because it seems to me like that did more good than harm. Does that mean I support the (mostly) “nonviolent genocide” of Imperial Japanese culture?

That’s a slightly better point. The main argument for genocide though is, that a whole population is forced to erase their culture. The population of japan could have chosen to ignore the obviously forced statement and continued to believe in their faith. And it seems like they did if shinto is still a thing, even if it is struggling like many other religions are.