Things I wish I could have said to the perpetrator before it happened:
1. You might think that you are waking people up to the threat of Islam. But it's far more likely that they'll wake up to the threat of you and whatever movements you claim to support.
2. Islamic terrorists have planned attacks against Norway. They've planned attacks in a lot of places. I plan to pay off my house and lose 25 pounds within five years, but it doesn't mean it's going to happen. Why not take a wait and see approach? If foreign terrorists do attack, you can say that you were right and more people will listen to you. If they don't, you can rejoice in the fact that your country has been unharmed by the current crisis.
3. Are you really doing this for the reasons that you claim? Do you really want Norway to become a police state? Or are you doing this for the notoriety and the attention? Do you think that 100 years from now, historians will say "Boy, it's a good thing that this guy killed all those people"?
4. Lie face down on the ground, and put your hands behind your head.