A stable, terrorist-free Iraq is key to the protection and survival of Western civilization. Since the U.S. took the war to our enemy after 9/11, after over 30 years of sitting idly by doing little or nothing about the growing problem, almost all terrorist activity has occurred in Muslim countries like Iraq, Pakistan, India, Bangladesh, and some in places like Saudi Arabia, Afghanistan, the Philippines, Thailand and Indonesia.
Iranian-backed Shias have joined the Radical Islamic Muslims to try to control Iraq after the ouster of dictator Saddam Hussein, as they battle the Al Qaeda-backed Sunnis in an effort to establish a worldwide caliphate (Islam rules the planet) centered in Iraq. Al Quada, ruled by Shia clergy for 20 years, wants the Shia to lead the caliphate, and Iran, (a mostly Shia nation ruled by the Sunnis for centuries) want a Sunni-led caliphate.
When you look at the violence and death in Iraq, it has much less to do with the United States, and much more to do with two terrorist entities battling for control of a land from which to establish the caliphate.
If the US backs out of Iraq and allows the two factions to continue their fight for the control of Iraq, it will be a losing situation for Western civilization no matter who wins. Iraq has the resources and geography to fund the caliphate, and according to Osama bin Laden, Iraq will be the center of that caliphate. Iran seems to agree with Al Queda, at least with that.