Sectarianism is a form of bigotry, discrimination, or hatred arising from attaching relations of inferiority and superiority to differences between subdivisions within a group. Common examples are denominations of a religion, ethnic identity, class, or region for citizens of a state and factions of a political movement. The ideological underpinnings of attitudes and behaviours labelled as sectarian are extraordinarily varied. Members of a religious, national or political group may believe that their own salvation, or the success of their particular objectives, requires aggressively seeking converts from other groups; adherents of a given faction may believe that for the achievement of their own political or religious project their internal opponents must be converted or purged. Sometimes a group that is under economic or political pressure will kill or attack members of another group which it regards as responsible for its own decline. It may also more rigidly define the definition of...