For years, Grand Ayatollah Hossein Ali Montazeri criticized Iran's supreme leader and argued that the country was not the Islamic democracy it claimed to be, but his words seemed to fall on deaf ears. Now many Iranians, including some former government leaders, are listening. Montazeri has emerged as the spiritual leader of the opposition, an adversary the state has been unable to silence or jail because of his religious credentials and seminal role in the founding of the republic. He is widely regarded as the most knowledgeable religious scholar in Iran and once expected to become the country's supreme leader until a falling-out with Ayatollah Ruhollah Khomeini, the leader of the 1979 revolution and Iran's supreme leader until his death in 1989. Now, as the Iranian government has cracked down to suppress the protests that erupted after Iran's presidential election in June, Montazeri uses religion to attack the government's legitimacy. 'We have many intellectuals who criticize this regime from the democratic point of view,' said Mehdi Khaliji, a former seminary student in Qum and now a senior fellow at the Washington Institute for Near East Policy. 'He criticizes this regime purely from a religious point of view, and this is very hurtful. The regime wants to say, 'If I am not democratic enough that doesn't matter, I am Islamic.' 'He says it is not an Islamic government.' Now in his mid-80s, frail and ill, Montazeri has remained in his home in Qum, the center of religious learning in Iran, issuing one politically charged religious edict after another, helping keep alive a faltering opposition movement. The man whom Khomeini once called 'the fruit of my life' has condemned the state he helped to create. 'A political system based on force, oppression, changing people's votes, killing, closure, arresting and using Stalinist and medieval torture, creating repression, censorship of newspapers, interruption of the means of mass communications, jailing the enlightened and the elite of society for false reasons, and forcing them to make false confessions in jail, is condemned and illegitimate,' he said in one of a flurry of written comments posted on his Web site and opposition Web sites since the election. While Iran's current supreme leader, Ayatollah Ali Khamenei, has limited religious credentials, Montazeri, a marja, or source of emulation, has achieved the highest standing a cleric can hold in Shiite Islam. He is also the architect of Velayat-e Faqih, or guardianship of the jurist, the foundation of Iran's theocracy and the source of the supreme leader's legitimacy. Indeed, when Khamenei was a student, Montazeri was one of his teachers. 'He is able to delegitimize Khamenei more than anybody else on the Earth,' Khaliji said. Some Iran experts argue that Montazeri's involvement in politics has undermined his religious credibility, and that he does not have as large a following as other grand ayatollahs. But there is evidence, others say, that the recent conflict has increased his popularity among a younger generation that knew little of him, and that his religious edicts resonate with Iran's pious masses. Despite the arrests of thousands of protesters and reformists, many who have complained of torture and even rape, the government has failed to silence the opposition, led mostly by the clerics who built the Islamic Republic from the earliest days: a former prime minister and presidential candidate, Mir Hossein Mousavi; a former speaker of parliament and presidential candidate, Mehdi Karroubi; and a former president, Mohammad Khatami. These men have now adopted positions that Montazeri has argued for years, that even in a religious state legitimacy comes from the people. 'The government will not achieve legitimacy without the support of the people, and as the necessary and obligatory condition for the legitimacy of the ruler is his popularity and the people's satisfaction with him,' he said last month in response to questions the BBC sent to him. In the early years of the revolution, Montazeri did not attract a broad following, in part because he was so plain-spoken. He was mocked by the elite and the middle class. Despite Montazeri's religious learning he came off as a sort of country bumpkin. In one joke that circulated after the revolution, he visited a medical school where students were studying to be pediatricians. Montazeri, the joke went, told them that if they studied harder they could become doctors for adults. He was embraced by Khomeini because he promoted the concept of Velayat-e Faqih, which called for a religious leader to reign supreme over the government. The concept was ultimately embedded in the bedrock of the Islamic Republic. But Montazeri has also repeatedly said that he meant the faqih, or leader, should serve as an adviser, not as the final arbiter of all matters of state and religion. Montazeri's disillusionment, and his alienation from the state, came within a decade of the revolution. He mocked Khomeini's decision to issue a fatwa calling for the murder of Salman Rushdie, author of 'The Satanic Verses,' saying, 'People in the world are getting the idea that our business in Iran is just murdering people.' The breach with Khomeini became irreparable in January 1988, when Montazeri objected to a wave of executions of political prisoners and challenged the leadership to export the revolution by example, not by violence. 'He was not willing to sell his soul to stay in power,' said Muhammad Sahimi, a professor at the University of Southern California. The next month, Khomeini criticized Montazeri in a letter and then forced him to resign as his deputy and heir apparent. He returned home to Qum where he remained relatively quiet until the rise of the reform movement, which he embraced. In 1997, Khamenei placed him under house arrest, which was lifted in 2003 under growing political pressure. 'There is no one else in the current leadership of the Green Movement who risked as much, as publicly, as early, as consistently as he has, and has lost as much,' said Abbas Milani, a professor of Iranian studies at Stanford University who as a young man shared a jail cell with Montazeri during the time of the shah. In recent times, Montazeri has kept up the pressure, taking the unprecedented step of apologizing for his support for the 1979 takeover of the U.S. Embassy. He also has said that the Islamic Republic is neither Islamic, nor a republic, and that the supreme leader has lost his legitimacy. 'Independence,' he said in a recent speech on ethics, 'is being free of foreign intervention, and freedom is giving people the freedom to express their opinions. Not being put in prison for every protest one utters.' 