If a gangster says what he does is right, is he really right? What is really the definition for righteousness?

That day, I was, as usual, going online on face book and I saw this very interesting post my classmate, Shuin Kang, had put there: Tell me what right is, and why right is." He also brought up an example: if a gangster says he is really right, is he really right? Well, I feel that righteousness is, to put it simply, not to commit any sins or wrongful actions. The law has been set to enforce righteousness in the first place, and while there are undeniably certain loopholes in the law itself, it states clearly the principle of not committing sins, of not do actions that are clearly against moral value and conscience. Hence, I feel that the reason why we should even obey the law in the first place is not because we do not want to be punished by the higher authority, it is we, as humans, want to live side by side in peaceful harmony, and not go around doing wrongful actions that affects others negatively

I decided to bring up a quote from Shuin Kang himself," What is right is unchanging. How can you persecute someone and later claim that he is right? No. Right does not change. People change. What they think is right change. Right is free from error, and free from humans." I agree with him only partially, as I feel that this statement is, in a way (at least, only to me), very pessimistic. What is right, indeed is unchanging, and when people change, to be more selfish and greedy, their definition of right changes correspondingly too. I don't really agree that right should be free from humans though (no offence shuin kang XD). Righteousness has been displayed by certain noble people, who spend almost all their lives trying to benefit mankind (like Thomas Edison),and hence this shows that right is a virtue that is displayed by people (though sadly, not all), hence it is, therefore, associated with humans.

In fact, right does not have a real definition, right is just shown through examples such as God, who goes around helping others and does not commit sins. We should just try our best not to commit as many sins as possible, as I believe that one would soon have his own punishment and retribution if he goes around doing sins.