No different is this hope, than that of the Japanese infantryman, or the Kamakazi, that went to certain death in banzai charges, and suicide missions: because militarized Shintoism at that time, held that the Emperor of Japan was DEITY.
Let that sink in. In other words, service to the emperor meant they were going to be secure for eternity.
I think you are quite correct. ISIS is fighting for god (small "g") and the Iraqi army is fighting for the last guy that happens to be in power or maybe their families but based on what I have seen neither is much of a motivation.