Demographics of Iraq
97% of Iraqis follow Islam: 61% Shia and 34% Sunni. 1% of these describe themselves as "Just a Muslim". According to the CIA Factbook, Shias make up 60% of population, while Sunnis 35%. Christianity accounts for 5%, and the rest practice Mandaeism, Yazidism and other religions.
Sectarian violence among Muslims
Following the 2003 Invasion of Iraq and subsequent fall of Saddam Hussein's regime, the minority Sunni sect, which had previously enjoyed increased benefits under Saddam's rule, now found itself out of power as the Shia majority, suppressed under Saddam, sought to establish power. Such sectarian tensions resulted in a violent insurgency waged by different Sunni and Shia militant groups, such as al-Qaeda in Iraq and the Mahdi Army. Following the U.S. withdrawal in 2011, violence has increased to 2008 levels.
In February 2006, more than 100 people were killed across Iraq, when violence between the two Muslim rival sects erupted. It has left over a hundred people dead and dozens of mosques and homes destroyed.
The Grand Mufti of Saudi Arabia, Abdul-Aziz ibn Abdullah Al Shaykh, issued a fatwa on 12 September 2013 that suicide bombings are "great crimes" and bombers are "criminals who rush themselves to hell by their actions". Sheikh described suicide bombers as "robbed of their minds... who have been used (as tools) to destroy themselves and societies."