Would you call someone who's primary goal is to due good deeds a "good person"? Would you call someone who's primary goal is to due reprehensible deeds a "reprehensible person"?
People certainly can change over time, but someone's state at a given time is what that person actually is at the time.
I wouldn't think either of those people exist, from anyone else's perspective.
I envy your innocence, but sadly, the world has many reprehensible people in it.
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?
Are Palestinians terrorists?
There are indeed people who repeatedly perform reprehensible deeds.