Abdullah bin Abdul Aziz
Saudi Arabia King Abdullah bin Abdul Aziz. Reuters

The arrest of an al Qaeda-linked militant in Lebanon accused of engineering the deadly suicide attack on the Iranian embassy in Beirut last November (which killed more than two dozen people and wounded 150) again highlights the bitter divisions between two of the most powerful forces in the Middle East: Iran and Saudi Arabia.

On Wednesday, Fayez Ghosn, the Lebanese caretaker defense minister, announced that Majid bin Muhammad al-Majid, the Saudi chief of the Abdullah Azzam Brigades, was arrested by Lebanese army intelligence services in Beirut. “He was wanted by the Lebanese authorities and is currently being interrogated in secret,” Ghosn added. Shortly after the Nov. 19 suicide bombing, the Abdullah Azzam Brigades had claimed responsibility for the murderous attack, making Majid a most wanted man.

But Majid is only a front man, claim both Hezbollah boss Hassan Nasrallah and his principal sponsor, Iran. Both groups allege that the bombing was the work of Saudi intelligence, who have been seeking to destabilize the close relations between Hezbollah, Iran and their common ally, President Bashar al-Assad of Syria. Iran also believes that the Saudi spy chief Prince Bandar Bin Sultan, who has aggressively called for military intervention in Syria to topple Assad, himself masterminded the Beirut embassy attacks.

Iran’s deputy chairman of national security and foreign policy committee of parliament, Mansour Haqiqatpour, told Press TV, an English-language Iranian broadcaster: “During a trip by [the] Iranian parliamentary delegation to Beirut, we immediately declared after investigations that the Saudi footprint in the blasts was evident and conspicuous.” Iran and Nasrallah contend that Majid is working directly under the auspices of Saudi intelligence.

However, the Saudis have denied any complicity in the Beirut killings and distanced themselves from Majid. In fact, Agence France-Presse reported that Saudi officials “hailed” the arrest of Majid and condemned his activities. Al Majid “is a terrorist who attacked his own country before attacking the Iranian embassy [in Beirut]. The [Saudi] monarchy has been searching for him long before he staged this,” Saudi envoy Ali Awad Assiri told the Al Hayat newspaper. “He has been wanted by the Saudi courts for a long time,” Assiri added.

Iran and Hezbollah are also alarmed by the Saudis' decision to donate some $3 billion to the Lebanese military (to allow Beirut to purchase weapons from France), a move widely seen as a way for Riyadh to diminish the power of Hezbollah, which controls a large swath of Lebanon. One could assert that Iran and Saudi Arabia have already launched “proxy wars” in Lebanon, Bahrain and elsewhere, where they both seek to establish and maintain their influence.

But this is only the latest episode in a long and tangled history between Saudi Arabia and Iran. “Tension, rivalry and hostility have long characterized the bilateral relations between Saudi Arabia and Iran,” said Dilshod Achilov, a professor of political science at East Tennessee State University. “Both states have a laundry list of unresolved issues, which keeps the tension at all-time highs in the Persian Gulf.”

But Achilov does not think such hostilities will lead to war between the Mideast rivals. “Both [countries] realize that the costs would be too high on both ends,” he said. “Thus, neither Iran nor Saudi Arabia would want to go to war with one another.” Without a doubt, a military conflict between two countries would devastate the world economy (oil prices would skyrocket beyond reason), Achilov added.

One of the most important aspects of the seemingly intractable hostilities between Teheran and Riyadh have to do with religion – Saudi Arabia is a kingdom dominated by Sunni Islam, while Iran is a Shia Muslim power. This ancient conflict between Sunnis and Shias has already led to bloodshed and sectarian wars across the Muslim world, including Iraq and Pakistan. But how and why did this schism occur?

The split goes all the way back to the death of the Prophet Muhammad in the year 632 and it had to do with succession – that is, who would be the rightful successor to the Prophet? Essentially, those who became Sunni believed that the heir to Mohammad should be determined by the community of elder Muslim clerics. To the contrary, those who became Shias (a distinct minority), felt Mohammad’s successor should come from the Prophet's own family, namely Ali, his son-in-law -- since Mohammad had no sons who survived into adulthood.

Soon after, the Sunnis got their way and chose another successor as the first caliph. Ali eventually became the fourth caliph -- but by then it was too late, the cracks had already formed. In fact, Ali's selection prompted a war leading to his own death in 661 in Kufa, in present-day Iraq. The relationship between the Shia and Sunni would forever be ruptured.

Moreover, it was Ali's son Hussein who perhaps became the most potent symbol to Shia Muslims. Hussein launched a war against the reigning caliph -- a bloody battle that led to his own gruesome death. Hussein was decapitated and his severed head was carried to the Sunni caliph in Damascus as a tribute. His (headless) body was left on the battlefield at Karbala (present-day Iraq), where it was later buried.

Consequently, Hussein became an eternal martyr for the Shias. For the past 15 centuries, Shia Muslims commemorate Hussein's death by self-flagellation in a public ritual called Ashoura. Another key difference between Shias and Sunnis has to do with how they address and regard their senior clerics. Shias call their leaders Imam (Ali was the first Imam, Hussein, the third). The Sunni clerics have no such glorified equivalent.

Yet another key theological dispute between the warring camps has to do with the idea of a Messiah. As with Jews and Christians, Shia Muslims believe that the 12th (and last) Imam -- who lived in the 10th century and vanished, and is known as the Mahdi -- will return to earth at the end of time. In Iran, the ayatollahs serve as caretakers of the faith until the Mahdi returns. Sunnis find this belief anathema. On the other hand, Shias frequently curse the original Caliphs so revered by the Sunnis.

One thing to remember is that Sunnis represent an overwhelming majority of the global Muslim population – perhaps as much as 85 percent to 90 percent, according to scholarly estimates. Indeed, the only major Muslim country dominated by Shias is Iran, although significant Shia communities exist in Iraq, Lebanon, Saudi Arabia, Syria, Afghanistan, Yemen, Pakistan and India. Moreover, Yitzhak Nakash, author of "The Shias of Iraq," estimates that Shias account for some 80 percent of the population in the oil-rich Persian Gulf region (which includes Iran, southern Iraq and eastern Saudi Arabia), thereby providing them with considerable economic leverage.

Iran (ancient Persia) became a Shia kingdom in the 16th century with the arrival of the Azeris and the establishment of the Safavid dynasty. Iran was thus surrounded by Sunni empires to the east (Mughal India) and to the west (Ottoman Turkey).

In the realities of the present day, Saudi is just as worried about Iran’s nuclear program as Israel is. According to Foreign Policy, in the summer of 2010, Saudi King Abdullah told Herve Morin, then the French defense minister, that: "There are two states in the world that do not deserve to exist: Iran and Israel." Abdullah has also repeatedly urged Washington to attack Iran and destroy its nuclear facilities, diplomatic cables unearthed by Wikileaks revealed.

But Khosrow Soltani Kaseb, a journalist based in Tehran, suggested that Iran’s new president, Hassan Rouhani, may offer a more moderate stance with respect to Iran-Saudi relations. Indeed when Rouhani gained election in June, King Abdullah sent him a congratulatory telegram and praised his conciliatory remarks toward the Kingdom. “The new leaders in Iran seem to appreciate Saudi Arabia's positive role in regional developments,” Kaseb wrote. “They are also aware that a confrontational mode of interaction between Iran and Saudi Arabia would benefit neither country, but produce negative consequences for the entire region.”