(RNS) — The killing of Ayatollah Ali Khamenei, Iran’s supreme leader for nearly four decades, on the first day of the U.S.-Israeli war on Iran is triggering starkly different reactions in the Middle East and around the globe. Not only the Muslim world’s longest-serving ruler, Khamenei was also one of the most powerful Shiite clerics in the world.

Among Muslims, the responses are split mostly along sectarian lines. Despite his tyrannical rule that killed more than 7,000 Iranians just in the past eight months, many in Iran, a majority Shiite nation, are mourning Khamenei as a martyr. Hundreds of others have been captured on video celebrating his demise, chanting and dancing in jubilation. 

The broad range of Iranians’ reactions reflects the country’s political diversity, said Mehdi Shadmehr, associate professor of public policy at the University of North Carolina at Chapel Hill, who compared the ideological split in Iran to the United States.

“When Trump won the 2016 or 2024 elections, some were very surprised that so many people voted for Trump,” Shadmehr told RNS via email. “We should not be surprised that some Iranians liked Khamenei.”

Khamenei was the highest religious authority in Iran. The senior clerics in Shiite Islam, practiced by approximately 10% of Muslims worldwide, hold massive religious authority, which Khamenei seamlessly merged with political power at home and regional influence across the Middle East.

Unlike Sunni Islam’s highly decentralized structure, Shiism maintains a hierarchy of trained religious scholars. The schism between the two groups began in 631, when a dispute arose over who should lead the Muslim community after the Prophet Muhammad’s death. Iran is more than 90% Shiite, and its adherents also make up the majority of Muslims in Iraq. But Shiites are scattered in pockets across the Middle East.

This historical split continues to permeate the lives of Muslims around the world, often showing up as political sectarianism, even crossing national borders. As a supreme clerical authority, Khamenei was seen as a sacred leader and protector of Shiite power globally.

“He was an important symbol for Shias around the world. He was somebody who was the political and religious leader of the only sovereign Shiite state in the world,” said Raissa von Doetinchem de Rande, an assistant professor of religious ethics at the University of Chicago Divinity School. 

Khamenei represented the aspirations of Shiite communities, who tend to be conscious of their minority status within Islam, said von Doetinchem de Rande. 

In Lebanon, the Shiite group Hezbollah held a thousands-strong rally in the Beirut suburb where it holds influence. In Iraq, the government declared three days of mourning. The Shiite majority nation’s close ties with Iran’s rulers were kick-started by the 2003 U.S.-led invasion. 

In Syria, however, Khamenei’s death was welcomed as vengeance for his backing of former strongman Bashar Assad, who was overthrown in December 2024. Under Khamenei, Iran supplied Assad with militias and weapons and aided in reported massacres in Syria. 

But in a reflection of Khamenei’s political influence on the region, some Sunni Muslims also appreciated his firm rhetorical line against Israel, his global call on Muslim countries to support Palestinians and his development of Iran’s proxy strategy, in which Iran funded militant groups such as Hezbollah, Hamas in Gaza, the Houthis in Yemen and others to bedevil Israel.

Von Doetinchem de Rande said his position as the leader of a Muslim nation has caused many Muslims of all traditions to take his killing on Saturday (Feb. 28) at the hands of the U.S. and Israel as a rebuke to the Muslim faith itself. 

The deaths of more than 800 Iranians so far in the war — at least 175 of whom were students and others at a girls’ elementary school, according to The New York Times — have also upset Muslims who might otherwise have regarded the death of Khamenei as a net good.

“Whatever their feelings might have been about Iran or Shiite Islam beforehand,” von Doetinchem de Rande said, “this might be a moment where that recedes into the background, and what stands at the forefront is the fact that he was an important figure as a Muslim symbol, political and religious.” 

The hard-line Shiite cleric became supreme leader in 1989 after the death of Ayatollah Ruhollah Khomeini, who returned from exile in 1979 to lead a revolution against the Shah of Iran, a monarch whose family was propped up by Western nations after the government of Mohammad Mosaddegh was overthrown with the assistance of the British and U.S. intelligence services. 

Khamenei, like his predecessor, positioned himself as a staunch opponent of Western influence and imperialism, and a defender of the Islamic Republic of Iran.

The ayatollah swept to power in the country by embracing “Khomeinism,” a political philosophy that draws laws and legitimacy from God and that dictates that Iran would be ruled by a single Shiite scholar. 

Religious scholars say there are already signs that his status as a martyr is being woven into the Iranian narrative. The concept of martyrdom and succession is enshrined in the history of the Shiite experience, which traces its lineage to the historical schism and what Shiites believe was the wrongful succession of the leadership of Islam. 

Some early Muslims supported the Prophet’s close companion and father-in-law, Abu Bakr al-Siddiq, while others followed his cousin and son-in-law, Ali ibn Abi Talib, who would later be recognized by Shiites as the first imam.

Decades later, in 680, the conflict culminated in the Battle of Karbala in what is now Iraq. There, Hussein ibn Ali, the Prophet’s grandson and the third Shiite imam, was killed by the forces of Yazid ibn Mu’awiya, the second Umayyad caliph and ruler of the Islamic empire. 

Khamenei, the second supreme leader in Iran, was seen as a sort of successor in that religious history and was endowed with “all the authorities that the Prophet and infallible Imams were entitled.”