Here's Dabiq, ISIS's propaganda magazine.[1] It's well-produced and in English. See what the other side wants. There are the usual rants: "We ask Allah to support the mujāhidīn of the Islamic State against the agents of the tawāghīt and the crusaders until the banner of the Khilāfah is raised high above Istanbul and Vatican City". Their strongest ire is raised against Arabs who oppose ISIS. The West is just the enemy, but Islamists who oppose them are committing apostasy. They're opposed to democracy on principle. Allah must rule, and that means autocratic rule by religious leaders. "Legislation is not but for Allah".
There's a concern that some people will be taken in by this stuff. That's only a problem for people who haven't seen enough extremist material to be able to evaluate it. There's a certain similarity to all that stuff, along the lines of "We're good, because God is on our side, and we have to kill the other guys because they're evil." This message is available in Christian, Jewish, and Islamic flavors. Kids should see all of those in school, to immunize them against such messages.
Will "trusted flaggers" be allowed to make Dabiq inaccessable?
("Maybe they is not evil. Maybe they is just enemies." - Poul Anderson)
[1] https://clarionproject.org/islamic-state-isis-isil-propagand...