The division between Sunni and Shia Muslims is one of the oldest religious schisms in the Middle East - and is one that seems increasingly to be shaping the destiny of this troubled region as thousands of devotees from both sides pour into Syria. Jihadist al-Qa'ida volunteers on the Sunni side and Hezbollah militants on the Shia side, are joining what is fast becoming a transnational civil war between the two factions.
There are around one and a half billion Muslims in the world. Of these, somewhere between 10 and 20 per cent - estimates vary considerably - are Shia. In most countries these Shia are minorities in a Sunni homeland. But in Iraq, Iran, Bahrain and Azerbaijan they outnumber their co-religionists.
What makes Syria different is that there a Sunni majority is ruled by a Shia minority. The Alawites, the sect to which President Bashar al-Assad and much of his army officer elite belong, are Shia. That situation is the mirror opposite of Iraq under Saddam, where a Sunni strongman lorded it over a Shia majority - until the invasion of Iraq, when elections put the Shia in charge, insofar as anyone can be said to be running that chaotic country.
The rift between the two biggest Muslim factions goes right back to the beginning - and a row over who should succeed the Prophet Mohamed as leader of the emerging Islamic community when he died in the early 7th century.
In the last 10 years of his life Mohamed inflicted total defeat on the pagan tribes of Mecca and by doing so united the entire Arabian peninsula. Around 100,000 people had submitted to the rule of Mohamed and of Allah. Tribal alliances in Arabia in those days usually disintegrated on the death of the leader, or after the short-term military objectives had been met and the spoils divided. Often succession would pass to the leader' s son. But Mohamed had no son, only a daughter. And his inheritance was spiritual as well as political.
The majority of his followers thought his closest associate, Abu Bakr, should take over. They became the Sunnis. But a minority thought the Prophet's closest relative, his son-in-law and nephew Ali, should succeed. They became the Shia.
Shia is an abbreviation of Shiat Ali "the party of Ali". Intrigues and violence followed, with Mohamed's widow Aisha (who was also the daughter of Abu Bakr) leading troops against Ali. Eventually Ali was killed, as was his son Hussein, and persecution and martyrdom became ingrained in the Shia psyche. As the years passed rift hardened into schism. The seeds of civil war had been sown.
The two sides agreed on the Quran but had different views on hadith, the traditions recorded by Mohamed's followers about what he had said and done in his life. Diverging traditions of ritual, law and practice soon emerged. A clerical hierarchy, topped by imams and ayatollahs, became crucial in Shi'ism. By contrast, Sunni Muslims felt no need of intermediaries in their relationship with God - an approach which has abetted the rise of extremist zealots like al-Qa'ida. The Sunnis became happy to depend upon the state, which their adherents mostly controlled.
The chief Shia religious festival became Ashura when devotees would beat themselves to commemorate the death of the Prophet's grandson Hussein at the Battle of Karbala in 680. Various Shia sub-sects formed, including the fanatical Assassins, the Alawites in Syria and the Ismailis, whose leader is the Aga Khan. Some mystical sufi movements created a bridge between Sunni and Shia but hardline Sunnis regard the Shia practice of venerating saints and visiting shrines as heretical - which is why Sunni extremists bomb Shias on pilgrimage in places like Karbala in Iraq today.
Two major developments have triggered the escalation of tension between Sunni and Shia in recent years. The first was the Islamic revolution in Iran in 1979 when the rule of the pro-Western Shah was overthrown and replaced with a Shia theocracy with Ayatollah Khomeini at the head.
The invasion of Iraq instigated by George Bush and Tony Blair in 2003 was the second big factor in the deterioration of Sunni-Shia relations. Saddam Hussein led a Sunni elite which governed Iraq's Shia majority with a reign of state terror. The US had backed Saddam in Iraq's war with Iran throughout the 1980s, in which half a million troops died. But after 9/11 the US changed its mind about Saddam, overthrew him and brought democracy to Iraq.
What all this means is that Sunni and Shia are locked in conflict all across the Middle East. As each side steps up its activities, the other feels more threatened and hardens its response in turn. Sunni-Shia tensions are increasing across the world as a result. They are on the rise in Afghanistan, Pakistan, Turkey, Kuwait, Lebanon, Bahrain, Libya, Tunisia, Malaysia, Egypt, and even in London as issues of identity, rights, interests and enfranchisement find sectarian expression.
The tensions are deep-rooted in wider economic and geopolitical concerns. But the risk - given the long history of division and tension - is that predictions of a transnational civil war between Sunni and Shia could become a self-fulfilling prophecy.
-- The Independent (19 February 2015)