It’s difficult for many people to understand how they can be this way because they have no understanding of how these people are raised and indoctrinated into these sects.
For many who join these terrorist groups it’s like Americans who grow up wanting to join CIA or Special Forces. Only they view it ‘all’ through the eyes of Islamic teachings.
They go around happily sawing off heads, drinking the blood and posing gleefully for photos while dripping with gore.
How could indoctrination alone explain such behavior? They must be possessed.