Sunni and Shi'ite Muslims represent the two major branches of Islam. The Sunni majority is spread around the world. The minority Shi'ites, many of whom live in Iran, account for about 15 percent of the world's estimated 1.3 billion Muslims. What is the impact of the religious divide between the two factions on rising sectarian tensions in the Middle East?
On the surface, it is hard to tell the difference between Sunnis and Shi'ites. They all believe Muhammad was their prophet. They all believe in the same holy book - - the Koran. And both sects uphold the five pillars of Islam -- daily prayer, fasting during the month of Ramadan, alms giving, the pilgrimage to Mecca and the belief in one god - - Allah.
But the split between the two main branches of Islam happened soon after the death of Muhammad nearly fourteen centuries ago. At issue was who should succeed him. Shi'ites rallied around Muhammad's cousin Ali, while Sunnis chose the best Muslim among them to succeed the prophet.
Religion and the State
Frank Peters, an authority on Medieval Islam at New York University, says Shi'ites believe that religious leaders should rule Muslim societies. The Sunnis reject that, he says, and their spiritual successors of Muhammad, although pious Muslims, are considered as only political figures.
"The Sunnis claim that as history unfolded was the way God intended -- that the community spoke through this process of choosing somebody to be his successor, not as a prophet, but as head of the community. It's the will of God that the community has both the church [i.e., religion] and the state," says Peters. "The Shi'ites don't believe that. They believe that it is just a spiritual community. They obviously have leadership and it has political power, but essentially it's a 'pope,' not an 'emperor,' who is in charge of the community."
Akbar Ahmed, an expert in Islamic studies at American University here in Washington and author of the new book A Journey in Islam, says when the Persians converted to Islam, they adopted as sacred figures, Ali and his son Hussein. He adds that Shi'ites have a strong identification with the suffering of Hussein who, along with his followers, was slain by a Sunni caliph in the Iraqi city of Karbala.
"From that sense of injustice, the sense of martyrdom, the sense of standing up to authority of the story of Hussein, the Shi'ites developed a very exclusivist ideology of pride, of fair play, of justice, and of commitment to faith itself," says Ahmed.
Professor Ahmed notes that the Shi'ite clergy is more centralized and hierarchical than the Sunni religious establishment.
"The clerics are often learned people. They spend years studying, writing books and articles. And as they progress along this hierarchy, they have more and more respect in society. The ayatollahs, who are right on top of the hierarchy -- they are the senior most clerics -- [they] have a very special place in Shi'ite society. They are known for their wisdom and their scholarship," says Ahmed.
"Unlike Sunni countries, where the learned class is not terribly organized and they have also been pretty much in the pocket of the Muslim state for a couple of centuries, in Iran the clergy has always been independent of the rulers," says Frank Peters of New York University. "There is a regular pecking order of authority among the mullahs. And at the top of that hierarchy, where archbishops would sit in Christianity, is a line of ayatollahs."
Many experts point out that Shi'ites and Sunnis have been at odds throughout history. The Shi'ites often protest that they have suffered persecution and injustice at the hands of Sunnis.
But political scientist Juan Cole of the University of Michigan says the two groups in many places coexist peacefully. He contends the current civil strife between Shi'ites and Sunnis in Iraq is more about power than issues of worship.
"In Iraq, for instance, in all of the 20th century, there was very little explicit Sunni-Shi'ite violence. But since the fall of the Saddam Hussein regime, politicians and political entrepreneurs have tried to mobilize religious communities as the basis for coming to power. And that has caused a great deal of sectarian violence," says Cole.
Professor Cole says Sunnis and Shi'ites have opposite political goals in post-Saddam Iraq. "The Sunni Arabs of Iraq have been the dominant group in that country all through the 20th century. They were key to the formation of the state. They don't believe that the Shi'ite power in Iraq is legitimate. They don't believe that Shi'ites are actually a majority and [ie., Sunnis say] that they [Shi'ites] were put into power by Americans and kept there by Iranians," according to Cole. "The Shi'ites are happy about the changes that have occurred in Iraq. They are eager to see the Sunni Arab guerilla movement defeated."
Iran and Beyond
Some analysts, including Chris Toensing of the Washington-based Middle East Research and Information Project, say fears of Iran's regional ambitions have already sparked sectarian tensions in some Persian Gulf states and beyond.
"In most of the Sunni countries with large Shi'ite minorities, there has been a renewed wave of sectarian tension, some of which has resulted in inter-sectarian violence. Partly related to the Iraq War and to the perceived rise of Iran, there is a new sense of sectarian tension throughout the region," says Toensing.
But Toensing also says that Shi'ites and Sunnis often unite in defending common strategic interests. "An example is the Lebanon war last summer where Hezbollah, a Shi'ite militia, faced off the Israeli Army. Muslims throughout the Islamic world, including the Arab world, which is majority Sunni, were rallying to the defense of Hezbollah, even though in the early stages of the war the three most important Sunni Arab states -- Jordan, Egypt and Saudi Arabia -- were quite openly blaming Hezbollah for the devastation that was wreaked upon Lebanon."
Most analysts agree that this kind of Muslim solidarity usually trumps sectarian tensions on a local scale. They close ranks against common adversaries. But as the threat passes, their divisions reemerge.