That's an excuse to dehumanize people. Labeling people rather than deeds is simply an announcement that you're willing to compromise your own ethics in order to attack that person. It's what's really happening when we label people as terrorists.
As pharrington points out, your words imply that you agree with me that terrorists are reprehensible people, or you are trying to argue that terrorists don't actually exist. Which is it?
Do you believe terrorists exist? If no, would you say that Osama Bin Laden was not a terrorist?