There are certainly multiple things at play here. I think the three main ones are: 1. Religion 2. Politics 3. Personal gain For instance the politics around

There are certainly multiple things at play here. I think the three main ones are: 1. Religion 2. Politics 3. Personal gain For instance the politics around hating the west and hating Israel, and personal gain in sex deprived young men getting to rape women in Syria and getting a salary that's 5x as much as the average Syrian. These three parts are intertwined and can't be separated from each other. Most media focuses solely on #2, but a theory built solely around #2 does not explain the behaviour of ISIS very well, whereas a theory built around all 3 aspects fits the data very well. As for the idea that high ranking members of ISIS do not truly believe in the ideology, and they are just manipulating everyone for personal gain, it is possible but I consider it unlikely. The leader of the Heaven's Gate suicide cult also committed suicide himself along with the others. And George Bush is himself a true Christian believer. I consider it unlikely that ISIS is an exception. It is interesting that the only people equipped to intuitively understand the sincerity of the metaphysical beliefs of a suicide bomber are those who are or were in a cult or fundamentalist religion. For instance Megan Phelps-Roper who left the Westboro Baptist Church does understand this.