As is the case with many diseases, it is not easy to pinpoint exactly when sectarianism began attacking the body politic of the Middle East. Over the centuries differing interpretations of Islam led to theological rivalry and even flare-ups of hatred among scholars of each tradition. Although some Sunnis have always regarded the Shia as heretics, in general the two communities followed their own traditions peacefully, and in most instances intermingled without problems.
For much of the 20th century, the Middle East's military dictatorships or absolute monarchies ensured that allegiance to the state was paramount, thus suppressing religious identities. In Arab countries the Shia were granted freedom to practice their faith, but were generally denied access to senior positions and regarded as socially inferior. In Shia-dominated Iran, the secular Qajar and Pahlavi dynasties made sure that Islam had no political role.
The 1978-79 revolution in Iran that toppled the Shah and led to the country becoming an Islamic theocracy shattered the pattern. While not all Shia communities revered the new Islamic Republic's theological outlook, the revolution inspired and energised them. In Lebanon the Shia majority, no longer prepared to be treated as second-class citizens by the politically dominant Maronite Christians and Sunni Muslims, muscled their way into the political mainstream. They acquired military strength through the creation of the Iran-backed Hizbullah movement in the 1980s.
The awakening of Lebanon's Shia and the declared determination of Iran to export its Islamic revolution alarmed its predominantly Sunni neighbours, sowing the seeds of a regional sectarian schism with political dimensions. Former (Sunni) Iraqi President Saddam Hussein, with a Shia majority in his own country, saw revolutionary Iran as a major threat. In 1980, he launched what he hoped would be a swift and decisive war to snuff out the revolution. It was neither.
As the Iraq-Iran war ground on during the decade mutual rhetoric among Sunnis and Shia became more hostile across the Middle East. Politics in Lebanon had long been defined along sectarian lines. However, one consequence of the ousting of Saddam Hussein in 2003 was the emergence of a similar system in Iraq, paving the way for today's dangerous political fault line between Sunnis and Shia in the country.
One of the most damaging effects of the decades of authoritarian rule in the Middle East has been the suppression of political ideology and the failure to tolerate politics in the broad sense of the word. The secular nationalist parties, which enjoyed considerable support in the 1950s and 60s, failed to deliver on their promises and evaporated after the Arabs' catastrophic defeat in the 1967 war with Israel.
The emergence of the Shia Islamic Republic of Iran not only gave minority Arab Shia communities self-confidence, but also alarmed the Sunni majority who, by virtue of their assumed superiority on the political and social stage, had never needed to identify themselves by their faith. Gradually, sectarianism became a giant prism: the people of the Middle East viewed their neighbours through it and governments used it to size up their rivals in the region.
"With each new conflict the contagion of sectarianism spreads further."
So today, the conflicts in Iraq, Syria and Yemen are widely regarded as proxy sectarian wars between the Sunni and Shia powerhouses of the region, Saudi Arabia and Iran respectively. Within each country, it's true, some clerics speak in harsh and derogatory terms about both Sunnis and Shia. But the rivalry between the two states is essentially about regional power rather than religion. The problem is that the public perception on the Arab Sunni side of the Gulf has been influenced by the spread of sectarian rhetoric. This in turn is fuelling Iranian perceptions of Sunni hatred and intolerance of the Shia and Shiism in general. A prominent Grand Ayatollah earlier this month said that the most important jihad (holy war) that Muslims had to wage was to remove Saudi/Sunni control from the holy cities of Mecca and Medina.
Against this background it is hard to view conflict in the region in terms other than sectarian ones. Saudi Arabia believes that the military success of the Zaydi Shia Houthis in Yemen can be explained by the support they receive from Iran. The Saudi military airstrikes were justified in the context of the Arab Gulf states seeking to curb perceived Iranian Shia meddling in the region – in Bahrain, Iraq, Lebanon and Syria.
The reality is that Yemen is engulfed by a full-scale civil war, pitting powerful units of the army against one another. The Houthis and some tribal leaders have allied themselves with one half of the military, under the command of Yemen's former president, Ali Abdullah Saleh. Tribes with allegiance to internationally-recognised President Hadi are backing the other half.
With each new conflict the contagion of sectarianism spreads further. The perception of the Yemen conflict as part of a wider sectarian war between Saudi Arabia and Iran, for example, is in turn exacerbating tensions among the Sunni and Shia communities watching from afar – especially in Iraq and Lebanon. What is desperately missing from the region is a compelling political ideology that encourages the inclusion of different sectarian and ethnic communities.
The least inclusive and most intolerant group of all is the jihadi group ISIS, an enemy to mainstream Sunniism and Shiism alike, not to mention the smaller minority faiths in the Middle East. Logic states that it would be in the best interests of Saudi Arabia and Iran to put aside their differences and unite against the common enemy. This has not happened and is unlikely to do so while the vicious circle remains unbroken and each country's efforts to pursue regional strategies are viewed as skirmishes in a wider sectarian war.