Salman Rushdie likely understood he would cause a controversy when he published a novel titled The Satanic Verses. The book mocked or at least contained mocking references to the Prophet Muhammad and other aspects of Islam, in addition to and a character clearly based on the Supreme Leader of Iran. On February 14, 1989, that Supreme Leader, the Ayatollah Ruhollah Khomeini, issued just about the strongest response possible, calling on “all brave Muslims” to kill Rushdie and his publishers.

Although many of the most controversial things said about Islam and Muhammad in the book come from the mouths of disreputable or comic characters, it was undeniably critical and insulting. The title refers to passages said to have been removed from the Qur’an in which the Prophet spoke the words of Satan instead of God, and many were particularly incensed by the depiction of a brothel where the prostitutes shared the names of Muhammad’s wives. Khomeini, who had suddenly deposed a U.S.-backed monarch a decade before, was the leader of a group of clerics who had turned Iran into a theocracy. As such, he was perhaps the most prominent Shi’a authority in the world. Muslims around the world had already condemned The Satanic Verses—it was publicly burnt in Bolton, UK, sparked a deadly riot in Pakistan and was banned entirely in multiple Muslim countries—but Khomeini’s fatwa brought the controversy to new heights.

Booksellers the world over, including many Barnes & Noble stores in the United States, refused to sell The Satanic Verses for fear of retribution. Many that did sell it were bombed. Free speech advocates and anti-religious figures vociferously defended Rushdie, but many Muslim leaders and even moderate Muslim cultural figures outright condemned him or at least stated he had gone too far. Rushdie apologized both to the Ayatollah and to Muslims around the world in 1989 and 1990, but protests and violence continued. The novel’s Japanese translator was stabbed to death in 1991, while its Italian translator was critically wounded by an assailant. Rushdie later said he regretted apologizing.

A fatwa is a judgement issued by a religious scholar and can only be repealed by that same scholar, meaning that the fatwa against Rushdie could never be taken back after the Ayatollah’s death in June of 1989. In 1998, the Iranian government declared it would neither “support nor hinder” Rushdie’s assassination, and private groups inside Iran and elsewhere continue to raise money to put towards the bounty on his head. Though Rushdie has had to hire security teams and has received countless threats since the book’s publication, no assassin has yet come close to killing him. The author, who was knighted in 2007, said that year that he saw the fatwa as “a piece of rhetoric rather than a real threat.” While Rushdie remains unharmed, the backlash to his novel is responsible for dozens of deaths and injuries around the world, one of the deadliest—and possibly the most widespread—instances of conflict between religious fundamentalists and free-speech activists of the 20th century.