Convince west to declare war on Islam. Which will unite all of Islam together in self-defense. Establish a caliphate. Tax people if they don't convert. Must continue to expand the borders of the caliphate, as a religious requirement.
This.
Which is kind of oxymoronic... Because what they want is
impossible. Even if we in the West completely played into it.
1.
Islam will never unite. If you look at body-count, it's clear that internecine/sectarian violence within Islam kills orders of magnitude more people than Islam kills Westerners, Christians, Jews etc. And the fracture lines are deep indeed. Not even counting Sunni vs. Shia, just within Sunni, where one might think there's agreement... The rather brutal and repressive Saudi Wahabis vs. the more Salafi/Takfiris stance ISIS takes. One would think they're close cousins, but ISIS/ISIL considers most of Wahhabism, and other Sunnis who make the pilgrimage to be idolaters due to the Kaaba in Mecca etc.
And even if you could wipe away the sectarian problems, the national/regional ones that add a whole other layer of back-stabby complexity to it all... it just wouldn't function because they're so culturally handicapped. The endemic lack of trust beyond one's family or tribe etc. and the corruption would leave them hamstrung. Granted, this has worked in ISIS' favor, like how the Iraqi forces, trained and supplied by the US with helicopters and export M1 Abrams tanks... initially
fled before ISIS in a bunch of Toyotas with RPG's.
But ISIS has the same problems internally. Units cutting and running, all the foreign fighters drawn to jihad can also just as easily flee back to their homes if the going gets rough etc.
2. Ignoring #1 for the sake of argument, assuming the unified caliphate got established, regional/national militaries and their logistics were all integrated... They still lose to the U.S., NATO, and the "West". And that's assuming Russia and China sit it out, or hell, even if they actually help this putative Caliphate with logistics/weapons, hoping it'll weaken/destroy the West for them by proxy.
It would be a bloodbath. A turkey shoot. Imagine how Iraq fell in one week to us twice in Gulf Wars 1 and 2, but the whole region. And we'd bring air and naval assets into play that we never needed in Iraq.
And if it were "total war" without occupation, nation building, or hearts-and-minds stuff afterward, and civilian/economic targets were on the table and not just military ones, it could conceivably depopulate the Middle Eastern Muslim population by something like 50 to even 90% within a year through infrastructure collapse.
I mean... Israel, all alone, defeated what arguably would have mostly comprised such a caliphate army three times in the 20th century. Imagine what the U.S./NATO would do to them.