In regards to Jones and the people in Afganistan who committed those murders, we see the example of religious extremism. Extremists in all theirs forms are dangerous, in my opinion. Being an adherant of a religion is not a bad thing, and in most cases shows a concern for community and a need for introspection that can be deeply fullfilling psychologically.
But in all endeavors there is the risk of the individual or group obsessing and becoming addicted to the negative feelings that can occur alongside the positive ones. In the case of religion, dogma and a hierarchechal power structure can lead to some people becoming obsessed with said religion.
For Islam, there are extremists that see their religion as the only source of stability in their life, and the dogma created by the religion also engenders a certain theocracy that attracts those who crave power.