It's easy to point to the Salafists, because they are often the most obnoxious and vicious in their rhetoric and well-funded by their official and private Gulf backers.
But there are no clean hands.
The Muslim Brothers agree with them on many matters of intolerance, especially against Shiites.
Some Iranian and other Shiite leaders in the region return the affection in full, with catalogues of anti-Sunni calumnies. Many backers of Bashar al-Assad, often themselves sectarians, paint all Syrian rebels as flesh-eating al-Qaeda Sunni monsters.
Disaffected Christian communities, particularly in exile, seethe with undisguised and irrational rage. Israel is seeing a rapid rise to prominence of racist, annexationist Jewish chauvinists, unabashed backers of a separate and distinctly unequal “Greater Israel,” and practitioners of "price tag" violence.
In the absence of local, national and regional order, hate-mongers deliberately set in motion the process of demonization in their own narrow, parochial interests.