You can justify a lot of actions with this motto. If you commit terrorist acts using this as your mantra, you will quickly become what you despise, and worse.
Agreed. The line between freedom fighter and terrorist is a thin and blurry one. We must remember that "terrorism" is a tactic, not a cause.
Would the British not have labeled the Boston Tea Party as an act of terrorism? Probably.
Or the militias of Concord a band of radical insurgents? In fact they did.
Terrorist/Insurgent is a label you put on your enemies.
Freedom fighter/Patriot is a label you give to your allies.
Obviously, something like blowing up a school full of children is a reprehensible act and can never sanely be defended.
But an act such as bombing a bus full of soldiers that is occupying your country is quite a different story.
Trying to understand a persons motives is not to be confused with defending their actions.
A biting dog may be acting out of fear and not anger, but that does not prevent me from kicking him away with a solid boot. And if you ask witnesses who the aggressor was, you will most likely get different answers.