The University of California Berkeley is back at the center of controversy in another battle over free speech, but this time there's a surprising twist of events.

A Berkeley radio station has canceled an August 9 speaking engagement with atheist author Richard Dawkins, according to Berkeleyside.

In recent months, the liberal university has generated widespread outrage for canceling speakers with conservative views, like Milo Yiannopoulos, Ann Coulter, and Ben Shapiro.

But this latest cancellation targets a well-known liberal.

Dawkins was going to speak about his new book, Science in the Soul: Selected Writings of a Passionate Atheist, in the engagement sponsored by KPFA.

Although Dawkins is outspoken against conservative values and Christianity, the radio station doesn't cite that as the reason for cancellation. Instead, KPFA sent a letter to those who bought tickets for the event saying it's because his views against Muslims could be taken as offensive.

"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 does not endorse hurtful speech," it says.

The letter condemns what they call "abusive speech."

"While KPFA emphatically supports serious free speech, we do not support abusive speech. We apologize for not having had broader knowledge of Dawkins views much earlier. We also apologize to all those inconvenienced by this cancellattion." In the past, Dawkins has criticized aspects of Islam on Twitter. In one tweet, he highlights the abusive treatment of some Muslim women.

Are you a woman bored with life in UK? Start a new life in our Caliphate as a SLAVE. If you change your mind, you can have a free beheading — Richard Dawkins (@RichardDawkins) July 6, 2015

In another, he references suggestions about what Mohammed would be doing if he were alive today.

It's been suggested that, if Muhammad were alive today, he would be a member of ISIS. Interesting to hear Islamic scholars' take on this. — Richard Dawkins (@RichardDawkins) April 1, 2015

Dawkins ended up responding to the radio station in a letter of his own: "I used to love your station when I lived in Berkeley for two years, shortly after that beloved place had become the iconic home of free speech," he wrote. "…I have criticized the appalling misogyny and homophobia of Islam, I have criticized the murdering of apostates for no crime other than their disbelief. 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."

In the letter, he points out what he sees as a double standard: "I am known as a frequent critic of Christianity and have never been de-platformed for that. Why do you give Islam a free pass? Why is it fine to criticize Christianity but not Islam?"

"You say I use 'abusive speech' about Islam. I would seriously – I mean it – like to hear what examples of my 'abusive speech' you had in mind. When you fail to discover any, I presume you will issue a public apology, which I will of course accept in a spirit of gratitude for what KPFA once was. And could become again," he added.