Prince Charles called on religious leaders to ensure their followers respect members of other faiths in a video message Tuesday, after a British extremist expressed sympathy for the killer of a Canadian soldier.

The future king of England said people of different faiths had lived together peacefully for centuries in the Middle East, with Christians and Muslims co-existing in the region since 700 AD.

“It is an indescribable tragedy that Christianity is now under such threat in the Middle East,” he said.

Charles went on to say that “our future as a free society” depends on “recognizing the crucial role played by people of faith.”

“My own Christian faith has enabled me to speak to, and to listen to, people from other traditions, including Islam,” he said.

“And as Pope Francis has recently said, such interfaith dialogue is a necessary condition for peace in the world, and should be seen as a duty for all Christians, as well as for believers from other religious communities.”

His call for peace comes as some fringe Muslim extremists in Britain, like Anjem Choudary, are rallying behind the Islamic State.

Choudary, who has more than 20,000 followers on Twitter, recently expressed sympathy for Martin Couture Rouleau, the Quebec man who ran down and killed Warrant Officer Patrice Vincent.

“He is my Muslim brother, I will pray for him to attain paradise no matter what mistakes he may have made in his life,” Choudary said of Couture Rouleau in an interview.