It has little, if anything to do with the "group".
It has everything to do with the individual reading the Holy Quran, or at least having heard verses of it 5 times every day of his life from the tops of minarets and in Mosques.
When one has that knowledge, he knows it is his duty to wage Jihad and kill infidels.
https://en.wikipedia.org/wiki/Raymond_Ibrahim
He’s one of the foremost experts on islam and is fluent in Arabic