Nick Cohen knows exactly:
Although it is impossible to count the books authors have abandoned, radical Islam is probably the greatest cause of self-censorship in the West today. When Ayatollah Khomeini proclaimed a fatwa against Salman Rushdie in 1989, censorship took the form of outright bans. Frightened publishers would not touch David Caute's novel satirising the Islamist reaction to The Satanic Verses, for instance. They ran away from histories and plays about the crisis as well because they did not want a repeat of the terror Rushdie and his publishers at Penguin had experienced.The mere fact that the writing of a certain kind of fiction, whatever its subject, can be called a 'national security issue' is an alarming indication of the extent to which the sinister parties of God have remotely suppressed the basic right to free speech throughout the world. Wherever the right to free speech is valued and upheld, it seems there are always those with a theistic agenda who wish to undermine this simple principle. Thus, editors are rarely faced with the prospect of government censorship, but must instead confront the hideous face of foreign theocracy. The fear of parody or satire is particularly noteworthy: if we cannot laugh at authority, we cannot possibly escape from it.
Such overt censorship continues. In 2008, Random House in New York pulled The Jewel of Medina - a slightly syrupy and wholly inoffensive historical romance about Muhammad's child bride Aisha - after a neurotic professor claimed that it was 'explosive stuff ... a national security issue'. Most of the censorship religious violence inspires, however, is self-censorship. Writers put down their pens and turn to other subjects rather than risk a confrontation. So thoroughgoing is the evasion that when Grayson Perry, who produced what Catholics would consider to be blasphemous images of the Virgin Mary, said what everyone knew to be true in 2007, the media treated his candour as news. 'The reason I have not gone all out attacking Islamism in my art,' said Perry, 'is because I feel real fear that someone will slit my throat.'
(Video: "People seem to expect Salman Rushdie to write about his experiences after a fatwa was imposed on him in 1989. He explains why he has not yet done it: At the moment it feels like reopening a room that I locked up for very good reason." Via TimesTalks.)