Tension between Sunnis and Shiites in Saudi Arabia (and elsewhere) increased following the Iranian Revolution in 1979, which replaced the shah’s government with a theocratic regime, the Council on Foreign Relations says:

The transformation of Iran into an overtly Shia power after the Islamic revolution induced Saudi Arabia to accelerate the propagation of Wahhabism, as both countries revived a centuries-old sectarian rivalry over the true interpretation of Islam. Many of the groups responsible for sectarian violence that has occurred in the region and across the Muslim world since 1979 can be traced to Saudi and Iranian sources.

One estimate found that since 1979, the Saudi government had jailed, exiled, or executed hundreds of Shiites. “Saudi recruits for al-Qaeda and the Islamic State group are often motivated by a desire to contain Shiism and stem Iranian influence in the region—strategic objectives that Saudi media perpetuates ad infinitum,” writes Toby Mathiessen. “Anti-Shiite (and anti-Christian and anti-Jewish) incitement is spread across the region by Saudi-based television channels.”

At the same time the revolution, in 1979, Nimr was leaving Saudi Arabia to study in Iran, as many Shia clerics do. He returned in 1994, where The Guardian reports he became well known to state security but remained otherwise obscure: “The kingdom’s intelligence services questioned him frequently, largely over his calls for increased religious freedom. He was eventually detained in 2003 for leading public prayers in his home village, where he had become an imam.”

In August 2008, a State Department official made a call on Nimr in al-Awamiyah. “The always controversial sheikh has gained extra attention over the past months by calling in bolder-than-usual terms for an end to anti-Shi'a discrimination in Saudi Arabia, and by seemingly endorsing the Iranian regime, its nuclear ambitions, and its increasingly active role in the region,” the official wrote in a cable released by Wikileaks. But the cable noted that “Al-Nimr is typically regarded as a second-tier political player in the Eastern Province.” The official noted that Nimr had been deploying anti-American rhetoric in his sermons more recently, but in person seemed far less implacably opposed to the United States—perhaps unsurprisingly, given that he was meeting with an American diplomat.

Nimr was overshadowed by more prominent Shiites—on one side, Hassan al-Saffar, who favored dialogue and reconciliation with the Saudi monarchy, and on the other by groups like Saudi Hezbollah that unapologetically backed violence against the state. Nimr told the State Department that the interfaith efforts were a “sham” and argued that only instability and tumult—rather than gradual change—would better the position of Saudi Shiites. But he hedged on whether he backed violence:

When asked by [a State Department political officer] as to whether his tough talk promoted violence or simply warned of it as a possible repercussion of continued discontent in the Shi'a community, al-Nimr responded that if a conflict were to occur he would "side with the people, never with the government." He continued by saying that though he will always choose the side of the people, this does not necessarily mean that he will always support all of the people's actions, for example, violence.

The State Department cable added Nimr was gaining popularity among young people. His stature grew in spring 2009, after Shia pilgrims clashed with security forces in Medina over access to holy sites; Nimr denounced the security forces, but then was forced to go into hiding to avoid arrest. By January 2010, the State Department reported in another cable that Nimr had returned home and was living under something like house arrest. The diplomat, who wrote that cable, judged that Nimr had overestimated his sway, gone too big, and as a result had lost his influence. A neighbor said that the government “chose not to pursue him further out of concern they would elevate his status.”