What Causes "Christian" Extremism? + Why Did Jesus Tell Us What He Told Us?? Reading John 16 #309 What Causes Religious Extremism?

Christian "extremists" have been in the news over the past few years - people doing violent or harmful things and claiming to do so in the name of Jesus, or in God's name. Such things have been going on for at least 2,000 years - what causes people to attribute terrible deeds to God or Jesus?