I want to say something because this discussion came up.
LTTE, Naxalites, Bodos started their revolution based on certain aim. Later some organizations crossed line. But because they want some land in Srilanka or Assam, they did not go and blast a train in Spain or England nor a resort in Bali.
Also, they never taught violence in the name of religion. It just happened that people living in that area are predominatly belongs to one religion. Also they never taught about viloence in their religious institutions.