OK...that’s 2.
Personal belief systems are naturally the result of personal choices and inclinations. So the whole thing is very much related, as we know, to thinking vs feeling.
It’s been known throughout the ages that the warriors of society are by nature passionate.
This factor is likely a significant driver.
(By the way, leaders of the subversive community are very aware of how the passionate character of war fighters can be used against them by targeting them with propaganda strategies.)