In 2005, violent protests erupted in Denmark and throughout the Muslim world in response to cartoons published in the Danish publication Jyllands-Posten, the most famous of which was a caricature of what appeared to be the Prophet Muhammad with a bomb in his turban, drawn by cartoonist Kurt Westergaard, who died this week at the age of 86.

More than fifty people were killed during the upheaval over the cartoons, and Westergaard lived the rest of his life under the constant threat of assassination from those who considered his work blasphemous. “I have no problems with Muslims,” he later told Reuters. “I made a cartoon which was aimed at the terrorists who use an interpretation of Islam as their spiritual dynamite.”

In 2006, CFI’s Free Inquiry magazine became the first national U.S. magazine to republish the cartoons, when no other American outlets would do so. The bookseller chain Borders pulled the issue from its shelves, for which it endured a great deal of criticism.

The entire episode of the cartoons’ publication, the violent reaction, and the global debate over the right to criticize religion that ensued is now commemorated every September 30 with International Blasphemy Rights Day, established by CFI in 2009.

“I want to be remembered as the one who struck a blow for free speech,” Westergaard has said. “But there is no doubt that there is someone who will instead remember me as the Satan who insulted the religion of a billion people.”