> it preaches the erasure of all other religions entirely
Within their relevant geographies, so does, it seems, the other movements.
I agree that Islamism is currently more in power and more violent, extreme and ridiculous than those others. But again, I’m not discarding anything they say as a result of it.
> Hindutva isn’t the same as either Islamism or Christian nationalism, since it literally means “Hinduness”
As it’s practiced it has involved excusing and in many cases encouraging murderous riots. (Islamism parsed literally also sounds innocuous.)
> a long-colonized people (Indians) trying to keep their culture from being erased by other powers
This is revanchism. All extremists do it. Islamists and Christian nationalists want a return of their golden ages.