Terrorists attacked a Paris newspaper office today, killing 12 people, including several cartoonists for Charlie Hebdo, its editor and two police officers. Another 20 were reportedly wounded, some of them seriously.

The attackers wore masks to hide their identity, but they made clear during the assault that their rampage was retribution for cartoons and other material published by Charlie Hebdo that had made fun of Islam and the prophet Muhammad, just as the publication had also satirized Christianity, Judaism, politicians and other public figures.

The gunmen are still at large.

By attacking Charlie Hebdo in such brutal manner, the Islamic extremists made it clear just how much they fear an open society and free-wheeling debate. They do not believe that their vision of society can co-exist with freedom of speech and freedom of conscience, and they're right. It cannot, which is why their vision of society is doomed and ought to be. They may have killed people, but they cannot kill the ideas that motivated those people. They will lose.

In fact, the attack drew immediate, horrified reaction from mainstream Muslim leaders. The Union of French Islamic Organizations said it condemned "in the firmest manner this criminal attack and these horrible murders." The head of the Arab League said he strongly condemned the attack, and Al-Azhar University in Cairo, the world's top Islamic education center, called it a criminal attack and denounced such violence as non-Islamic.

"This extremely grave barbaric action is also an attack against democracy and the freedom of the press," the French Muslim Council said in a statement. “In this tense international climate stoked by the madness of terrorist groups unjustly claiming to represent Islam, we call on all those attached to the republic’s values and to democracy to avoid provocation.”

Of course, for many none of that will matter. They will pretend not to hear it. No matter how vehemently it is condemned, the attack by Islamic extremists will be used by extremists on the other side to fuel resentment and fear of Muslims in general. And the irony is, that's precisely the response that the terrorists seek to provoke.

The extremists' best shot of gaining adherents is to drive a wedge between moderate Islam and the rest of the world, making it more and more difficult for Muslims to live peaceably and equitably in the western world. Make it impossible for them to open mosques, make it impossible for them to get jobs, make it impossible for them to live among us in mutual respect and peace. That too is the terrorists' goal, and to the degree that we cooperate in that goal, we surrender to them.

Do not surrender to them. Fight them, with the weapons of tolerance, respect and freedom that they fear most.