Bodos don't like your 'secoolarism' and conversion nonsense. Whether Christian, Animist or Hindus, they won't take nonsense from a bunch of foreigners. The Banglas thought they would be secoolar and bend backwards to accommodate their alien mentality.
Instead, they got their rears handed back.
It has to do with Muslims actually. Most of the muslims now in Assam and NE are not local but Bangla Muslims. And the tensions are not between Assamese Hindus, animists and Christians. It is a problem of all these three versus Bangladeshi Muslims who bring an alien religion and impose it onto local demography through appeasement politicians.