>>787857
Nagalanders were animists, not hindus.
Animists are usually easy-picking for monotheistic faiths, be they cathortodox, evangelical missionaries, or Islam(Buddhists are also easier to convert).
When you start competing with a religion that was actually there for a long time and has a developed canon, and/or one of the above mentioned monotheists, it gets tense, and it grows very slowly, unless a miracle happens, or you go full "Convert or die, infidel!", which isn't exactly the best strategy from a spiritual or PR point-of-view.