Saudi Arabia hates Iran more than it hates ISIS. The conventional wisdom is that ISIS is a radical Sunni group that is being funded by Sunnis in the gulf and opposed by Iran. But Iran is the arsonist and the fire brigade. Iran’s support for Assad and the [Nouri al-]Maliki government in Iraq led to many Sunnis supporting ISIS. It will have to be Sunnis who put out the ISIS fire.
Karim Sadjadpour, in an interview with Slate magazine, available here. Among other things, he highlights the interplay of sectarian and geo-political conflicts in the Middle East.