Changing your Facebook profile pic to the France flag colors is nice of you, but pointless. It's exactly what they want you to do.
You can pray, hope, and dedicate your life to ending terrorism in the world, and it won't make a damned bit of difference.
Pragmatic? Maybe. Realistic? Yes. Your prayers mean nothing to them. They don't subscribe to our religion, and the fact that you care so much only reinforces their desire to disrupt your life.
Terrorism means that they have disrupted your life to the extent that you now have to arrive at an airport two hours prior to takeoff, can't take certain things on board with you, and your entrance to sporting events means that you are guilty until proven innocent. That's what terrorism is.
So, go ahead and pray, hope, contribute money ... whatever your penchant. It won't matter. Sorry to tell you. The evil in the world is bigger than your good.
You can listen to the current presidential candidates when they tell you how they would deal with "those people," but their words will fall on deaf ears the next time ISIS or some other sect blows something up in the name of their religion.
Religion. That's the thing that got us here in the first place.