While many factors may play a role in the rise of ISIS, the end of days is the linchpin of ISIS ideology and propaganda. It drives everything.
In The Complete Infidel's Guide to ISIS, author Robert Spencer wrote:
“The Islamic State is thus positioning itself as the harbinger of the end times—of the final and decisive battle between the Muslims and the enemies of Allah, from which the Muslims will emerge victorious, after which peace—the peace of total Sharia adherence—will prevail over all the earth.”*
The Islamic State was proclaimed on October 15, 2006, and the announcement was based on a precise apocalyptic schedule.** ISIS believes their messiah will be preceded by an Islamic caliphate and views itself as the restoration of the caliphate—and thus, the harbinger of the end times.