"most of the north-east is converted [to christianity]" is surprising, but actually that's true, for several Indian states that are in the enclave eastern of Bangladesh (Nagaland, Mizoram and Meghalaya). Not "most" eastern states, though, only these ones.

I am certainly not in favor of acculturation, and I have no sympathy for religions such as christianity who advocate that nature exists just to be used by humans, however I am not sure that the current status is really evolving. These eastern states seem to have been converted long ago.