Reading the exquisite platonic dialogue Meno, I stumbled upon a principle, that may enlighten the debate about evil and good in our current societies, and may give us an inkling as to why the Islamic State has such stupendous success.
According to Plato, or Socrates, evil is the effect of stupidity or lack of knowledge. As a person gets wiser the person also gets less prone to evil.
This is a good reflection of IS I would say. Most of its combatant are gang members from different European and other countries. Not the most enlightened people.
These people then tend to follow the simple patterns and the easy answers. This is, again, what propels the forward to do evil deeds. Because the simple answers paint the brutes into a world with simple ideas.
If you are not muslim, you are an enemy. What a simple view of the world. It is easy to comprehend, you do not have to think much, just act according to this flawed, but simple logic.
This, at the other hand, gives an answer to the problem of eliminating the scourge to some extent; education.
G-d bless the will to be complex and humble in the face of knowledge.