It’s always disturbing when someone defends the suicide-bomber by suggesting that “one man’s terrorist is another man’s freedom-fighter”. Either they don’t know what terrorism is or their moral compass is pointing the wrong way.
Terrorists murder civilians to extort compliance with a political agenda. They deliberately sow fear to subjugate others to their will. You can’t be a “freedom fighter” by threatening murder to coerce compliance.
If terrorism is valid for one side, because they believe their cause is just, then it is also valid for the other side, who believe that they too are in the right. In the end there is chaotic destruction on both sides.
It doesn’t matter whether it is an IRA truck-bomb in London, a Palestinian suicide bomber, or a racist bombing a black church. The means themselves are evil, and can never be justified, not even by the most righteous ends.
There will always be disputes. Therefore the means of resolution must be means that can be used both now and in the future. Arbitration by discussion, by an impartial court, by democratically elected representatives are all valid because they achieve resolution without violence.
Ghandi ended the British occupation of India without violence. Racial segregation in the United States was ended by black people boycotting the buses, sitting at the “whites only” lunch counter, accepting arrest, and challenging segregation laws in court.
If your cause is just, then make your case through moral means. Speak, write, organize a boycott, go on strike, practice non-violent acts of civil disobedience, seek justice through the courts of law and public opinion. Patiently and persistently pursue a righteous objective until the world grants you justice. If they do not, then perhaps your cause is righteous only in your own eyes.