Silence means the religious fanatics that want to bring back the middle ages have won. That is not an acceptable result.
During the middle ages the Catholic church exercised a strong control over what got said and written. Errant behavior could be rewarded by torture or excommunication. The Pope excommunicated several kings of European countries to exercise control over them. The King didn't suffer, of course, only their subjects, trapped in a mindset where the ongoing approval of religious authorities was all important.
Mostly we've grown up, and are beyond that. Anyone that cares to look at it will quickly realize the Catholic church has been wrong about everything that can be verified. As Galileo said "And yet it moves."
There are two dangerous forms of religious extremism in the world today. One is Muslim fanatics willing to die to avenge so called insults to Islam and other related issues, and American Christian extremists.
Let's deal with the latter first. They hold some crazy ideas, and have a strong hold in the government of the USA. Generally they are trying to roll back the clock to when women were barefoot, pregnant, and in the kitchen. Without a vote. Dependent on their husbands for permission. Unable to take action to take care of their own reproductive health. They'd like to do away with Darwin and all his works, regardless of the damage to science. Mainly that's because they don't believe in the results of some science. Climate change is a big one. Certain biological truths around conception is another. There are more. I could bring up racist attitudes towards minorities, but that's a whole blog itself.
This end of the spectrum is a bit murky. There are guns and bombs and violence involved. The difference is that these people aren't shouting that Washington, or Rand, or Jesus, or other figure of idolation are being avenged. Mostly it's generic rage at "government" doing something that gores their ox, or so they think.
The Paris gunmen thought they were avenging the prophet Mohammed, a man dead for nearly 1400 years. My take on it is these religious figures can take care of themselves. If they're offended they can come deal with it themselves, in ways that are crystal clear to all involved. That hasn't happened, and I am confident it won't.
Those that think they are hearing voices telling them to do things like this? We know they are not divinely inspired. They are having mental health issues. They need treatment. The ones listening to figures of "authority"? They are pawns in a movement they don't understand, being used by leaders who are acting only for their own gain.
A religion that advocates stoning and beheadings as punishments for crime is not a religion of peace. Parts of it might be, but to the extent it's message can be twisted by extremists, that religion has to wear it, whichever it is. We see much lip service and hand wringing from some Muslim leaders, but what actions are being taken to curb the violence? Which Muslim states are taking action against other states that promote (actively or passively) such violence?
Let's tease out one thread in a complex cloth. There is a great deal of anti-American rage in the Muslim world and more particularly, the Arabic world, and for good reason. The British and American's have been meddling there for a long time. If people take on religion as a tool to help fight against what they see as oppression, I can hardly blame them. Attacks on military targets are legitimate, flying aircraft into office buildings is not.
I've said it before, and I'll say it again. We need to discuss issues openly and honestly. Things fester in the dark. In Canada, we need to talk about Native issues first, and then any number of other issues. The USA needs to get it's head straight around conception rights, and deal with the gun nuts, and many other things. Even bringing them up excites comment and heated discussion. At least here in Canada we don't generally worry about being shot or bombed in the discussion. In the USA being shot is a real fear.
But in much of the Muslim world even trying to talk about the role of religion in life, even in generalities is likely to lead to a riot. In some places there are teams of people ready to beat you with a staff if they think you are breaking their medieval rules. They want the world the way they want it, and are willing to be brutally violent about it. Talking has traditionally not had much result, so it's no surprise that the western world has often resorted to violence.
Except that doesn't work nearly so well. Afghanistan is a primitive country that has thrown two superpowers out, and is in the process of throwing out a third.
Toddlers sometimes threaten to hold their breath till they turn blue, or pitch a fit in the supermarket. Wise parents deal with it calmly. Maybe this is going to piss off some people, but these acts of violence from the Islamic world are very much like a toddler pitching a fit during the discovery that the world doesn't revolve around them.