Richard Dawkins is famous for criticizing religion in books such as The God Delusion, but a progressive radio station canceled the biologist's appearance due to his opinions on Islam.

KPFA, a community radio station in Berkeley, Calif., canceled Dawkins' appearance to discuss his book Science in the Soul when Muslim advocates complained, the Guardian reports. The station said that the science-based event would be tainted by Dawkins' "hurtful" opinions on religion and canceled it.

"We had booked this event based entirely on his excellent new book on science, when we didn't know he had offended and hurt—in his tweets and other comments on Islam—so many people," KPFA stated in an email to ticket-buyers. "KPFA does not endorse hurtful speech."

Dawkins published the email online, which laid out KPFA's views on speech.

"While KPFA emphatically supports serious free speech, we do not support abusive speech," the email reads. "We apologise for not having had broader knowledge of Dawkins's views much earlier. We also apologise to all those inconvenienced by this cancellation."

On the air, KPFA cited activists who said Dawkins was "a very well-known Islamophobe." It pointed to tweets and statements in which Dawkins said Islam is a force for evil and receives favorable treatment.

"You’re a homophobic misogynist."

"But I’m a Muslim."

"Oh, SORRY, I didn’t mean to insult your culture."https://t.co/8fQYmYGwLb — Richard Dawkins (@RichardDawkins) July 10, 2017

Dawkins struck back against KPFA's decision, and he has been defended by others in the academic community. He told KPFA in a statement that he had indeed criticized Islamism but was not an Islamophobic bigot.

"If you had consulted me, or if you had done even rudimentary fact-checking, you would have concluded that I have never used abusive speech against Islam," Dawkins said. "I have called IslamISM ‘vile' but surely you, of all people, understand that Islamism is not the same as Islam."

"Far from attacking Muslims, I understand—as perhaps you do not—that Muslims themselves are the prime victims of the oppressive cruelties of Islamism, especially Muslim women," he added.

Dawkins' criticism of religion is well known, although as an Englishman he has focused more of his writing on Christians. He asked KPFA about their seemingly unique sensitivity regarding Islam.

"I am known as a frequent critic of Christianity and have never been de-platformed for that," he wrote. "Why do you give Islam a free pass? Why is it fine to criticise Christianity but not Islam?"

Harvard professor and author Steven Pinker also defended Dawkins.

"He has criticized doctrines of Islam, together with doctrines of other religions, but criticism is not ‘abuse,'" Pinker said. "To criticize tenets of Islam is no more abusive than to criticize tenets of neoliberalism or the Republican Party platform."

Dawkins has earned recognition in the academy while criticizing religion fiercely for decades. In The God Delusion, he called the God of the Old Testament "arguably the most unpleasant character in all fiction."