Know your enemy. To know what ISIS is, we have to clear away the media myths about ISIS.
ISIS is not a new phenomenon.
Wahhabi armies have been attacking Iraq in order to wipe out Shiites for over two hundred years. One of the more notably brutal attacks took place during the administration of President Thomas Jefferson.
That same year the Marine Corps saw action against the Barbary Pirates and West Point opened, but even Noam Chomsky, Michael Moore and Howard Zinn chiming via Ouija board would have trouble blaming the Wahhabi assault on the Iraqi city of Kerbala in 1802 on the United States or an oil pipeline.
Forget the media portrayals of ISIS as a new extreme group that even the newly moderate Al Qaeda thinks is over the top, its armies are doing the same things that Wahhabi armies have been doing for centuries. ISIS has Twitter accounts, pickup trucks and other borrowed Western technology, but otherwise it’s just a recurring phenomenon that has always been part of Islam. Sunnis and Shiites have been killing each other for over a thousand years. Declaring other Muslims to be infidels and killing them is also a lot older than the suicide bomb vest.
Al Qaeda and ISIS are at odds because its Iraqi namesake had a different agenda. Al Qaeda always had different factions with their own agendas. These factions were not more extreme or less extreme. They just had different nationalistic backgrounds and aims.
The Egyptian wing of Al Qaeda was obsessed with Egypt. Bin Laden was obsessed with Saudi Arabia. Some in Al Qaeda wanted a total world war. Others wanted to focus on taking over Muslim countries as bases. These differences sometimes led to threats and even violence among Al Qaeda members.
Bin Laden prioritized Saudi Arabia and America. That made it possible for Al Qaeda to pick up training from Hezbollah which helped make 9/11 possible. This low level cooperation with Iran was endangered when Al Qaeda in Iraq made fighting a religious war with Shiites into its priority.
That did not mean that Bin Laden liked Shiites and thought that AQIQ was “extreme” for killing them. This was a tactical disagreement over means.