Why is free speech something you can be murdered for in Western Europe?

Shortly after the most recent, gruesome terror attack in France, security expert Eric Delbecque said, “Freedom of expression should not live under house arrest.” A history teacher, Samuel Paty, had been stabbed and beheaded near his school for showing his middle school students caricatures of the Prophet Muhammad during a class focusing on freedom of expression.
— Read on www.washingtonexaminer.com/opinion/why-is-free-speech-something-you-can-be-murdered-for-in-western-europe