Wahhabis (members of the Wahhabism, a fundamental Islamic group founded by Muhammad abd AlWahhab 1703-1792) threatened Iraq since the eighteenth century and they think that Muslims (especially the Shia) do not obey Allah and Koran because they visit the shrines of Ali bin Abe Taleb (Prophet Muhammad’s cousin) and his descendants and regard them as their Imams, which is considered ‘Kufr’ or disbelieve in God or polytheism, according to the Wahhabism, ‘because Allah said in the Koran: and if my adorers asked you about me, I am nearby, respond to a call of the prayer if he invocates’ and ‘the Mosques belongs to Allah so do not invocate to anybody else’, so there’s no need to go to those shrines and beg them for help, you must ask for help directly from Allah.
(Wahhabism has many other beliefs, but I just want to mention the history of it)
(Also I want to say that this movement tried to appear five centuries prior to Muhammed Abd AlWahhab, but it failed.).
So Wahhabis named their movement ‘AlTawheed’ since 1730 which means the belief in Allah only, and the other things (such as the holy shrines) are considered like the idols, and the one who visits them is a ‘Kafir’ and must be killed. That’s why the Shiites are Kafirs according to the Wahhabis belief.
Mohammad abd AlWahhab succeeded in his movement because he depended on the Bedouins in the desert of Arabia (now Saudi Arabia) and cooperated with their Emir (Bin Su’ood) those people do not care for the shrines or anything other than Allah, in addition to that, Mohammad abd AlWahhab stated ‘Aljihad’ for them to kill everyone who does not believe in their movement and that means they could raid on other tribes and places then kill their men, take their women and rob everything, such things were very effective especially when it comes with religion.
Since that time the movement was called (AlTawheed wa AlJihad)..
Then in 1790 the danger of the W. began to be clear in Iraq because it was easy to reach to the southern areas of Iraq from the Arabia, the W. killed people and robbed many places in Iraq who was under the Ottoman Empire at that time.
In 1802 the W. entered Karbal’a city when the people were visiting the shrine of Imam AlHussein in a day of the Shia called ‘AlGadeer day’, the W. used their swords to kill everyone there in one of the most ruthless massacres in the history of Iraq, they killed men, women and children in thousands, robbed the place and headed to AlNajaf but they could not enter because the residents of this city stood strongly against them so they ran away.
Iraq at a Glance: The Wahhabis