If you just state it's religious, you open up space for "Muslim bad", or "Christian bad" arguments. Which lead to nonsense and prosecution to specific peoples
If you use imperialism concepts, everything fits well together, and it leads to structural criticism of capitalism, and prosecution (to use the same word) against oppressive ideas and power structures, not against specific peoples.
But I can agree that imperialistic forces oppress religions that are not the same as theirs, if that's what you meant.