^Not all sunnis believe all shias should be killed nor do they declare all of them as heretics. For fucks sake I don't know of a single sunni muslim leader who controlled Mecca that stopped shias from going to Mecca-a muslim ONLY place!
But there has been Wahabi invasions in the 18th and 19th century against Karbala and Najaf which resulted in massacres of Shiites.
The government textbooks in Saudi Arabia disparages Shias and commends the Wahabi invasion.
From my personal experience which includes living in 2 Arab countries for considerable amounts of time, I found out that an overwhelming majority of Sunnis (and by proxy Arabs) HATE Shias.
The minute I landed in Egypt, my friends who were there before me advised me to lie and claim I was Sunni. The non-official student forum of the uni I went to there had a whole subforum titled (The Shias, Bahais, and the errors of their ways).
In Jordan they were a little straightforward. To my shock and disgust, the immigration officer asked me "Are you Shia or Sunni?"
This is the reason why pan-Arabism to Iraqi Shias (and many Iraqi Sunnis) is as Nazism is to Jews.
I could (and will if you want to) provide you with tens of youtube comments pages where the highest rated comments call for deportation of Shias from Saudi or applauds the 2005 Al-Qaeda bombing of a vaccination centre in the majority-Shiite south of Iraq that resulted in the death of more than a 100 mothers and their children, among other things.
Most importantly, the majority of the terrorist activities in Iraq that target civilians are carried out by foreign Arab nationals. (Baathists and Saddam loyalists only target coalition forces).
All the leaders of Al-Qaeda in Iraq have been foreign Arabs (as well as the majority of combatants and suicide bombers) [see:
http://en.wikipedia.org/wiki/Al_qaeda_in_iraq#Selected_key_members]
The 5 belligerents of the
recent attack on Christians in Iraq were all foreign Arabs. Before the 2003 war Christians were about 5%, now they are only 3% thanks to those Muslims you think "are sympathizing with Iraqis".