"Omnes moritatem. Deus suos cognoscet."   Kill them all, God will know his own" When asked how to seperate Catholics from Cathars,at the seige of Beziers July 1209 AD said by the papal legate Arnaud Amaury. 60,000 men women and children. Catholic extremists against fellow Christians. 1209-1255 an estimate of 1 million casualties.
So there are examples of religious extremism all over the world.