Max Fisher, Vox - Sunni-Shia sectarianism is indeed tearing apart the Middle East, but is largely driven by the very modern and very political rivalry between Iran and Saudi Arabia. They have sought to fight one another on Sunni-Shia lines not out of religious hatred but rather because they see sectarianism as a tool they can use — thus making that religious division much more violent and fraught. Debunking the "ancient hatreds" myth
Marc Lynch, a George Washington University professor and Middle East scholar, wrote a lengthy piece on this week's uptick in Iran and Saudi Arabia's regional cold war, which is playing out largely along Sunni-Shia lines, titled "Why Saudi Arabia escalated the Middle East’s sectarian conflict."
The piece was widely circulated by Middle East experts as authoritative and insightful. Some of the reasons Lynch discusses include: a desire to distract from Saudi foreign policy failures elsewhere, a fear that the United States is softening on Iran, and an effort to appease hard-line Islamist elements at home.
Noticeably absent from Lynch's list of factors: that Saudi Arabia hates the Shia due to theological disagreements or seventh-century succession disputes.
That's not a mistake. No one who seriously studies the Middle East considers Sunni-Shia sectarianism to be a primarily religious issue. Rather, it's a primarily political issue, which has manifested along lines that just so happen to line up with religious demographics that were historically much calmer and more peaceful.
This is not to say that there was never any communal Sunni-Shia violence before 1979. Nor is this to say that Iran and Saudi Arabia were the first or only countries to cynically exploit Sunni-Shia lines for political gain: Saddam Hussein did it too, and so have some Islamist groups. I want to be careful not to overstate this and give the impression that Sunni-Shia lines were completely and always peaceful before 1979, nor to overstate the role Saudi Arabia and Iran played in turning Sunni and Shia against one another. ""As usual, religion is a mere instrument of state ambitions""
But it is very much the case that Sunni and Shia differences have only quite recently become such a defining issue for the Middle East, and certainly that they have become so violent.