A civilized society is one where the rule of law prevails, not the rule of power. If an aggrieved group cannot achieve/is denied their desired outcome through valid, peaceful, judicial mechanisms, we generally do not recognise their right to then break their contract with the state and achieve their ends violently.
But if the group is victim of recognised human rights abuses and international law is on their side and against the state's, then I doubt that many would consider their subsequent resistance to the state's unwarranted power as the 'worst of crimes'. For instance, there's this movie right, with the Bond dude, and they're Jews, see, in Nazi Poland I think. Instead of comply with the system that would have them dead - a system that had clearly broken or waived any contract with its citizens - we deem them justified to, like, hide in the forrest and conduct partisan activities against such an evil force.
Or a better example is the Left Behind novels- AAaAah! What a joy they were in my developing years! We never would accept that Ellie was a 'terrorist' - we're behind her from the get go! JUSTICE doesnt have to be subjective