There's a difference between believing in absolute morality (which is what most people mean by right and wrong) and simply having the foresight and common sense to do good deeds and not to screw people over. One may be very kind, compassionate, and ethical without believing that one's own ideas of right and wrong are somehow inherent in the universe.

Actually, plenty of cultures have explicit definitions for what is right versus what is wrong. They are called laws, and are generally founded upon abstract principles or ideals.

Also, in order to 'not believe in right and wrong in the traditional sense', one has to implicitly acknowledge that, somewhere, there is a 'traditional sense', however vague.

Generally, human cultures are themselves formed upon little more than overlapping individual conceptions of right and of wrong; that's what the Rousseauian social contract basically states.

However, one does have the right to violate these implicit contracts with his or her neighbors on principle; this is called Civil Disobedience, which was practiced by Ghandi and Martin Luther King, Jr.

In modern societies, legality and morality have become at times mutually exclusive concepts, leaving morality to be decided upon a subjective, rather than objective basis.

For instance: Adultery in the US is usually considered to be immoral. It is not, however, considered to be illegal (unless you're in the military--but again, we are talking about MODERN societies, not archaic ones). This does not mean that the politicians in the US think adultery to be moral, but rather that it is left to the individual to make that decision.

Laws exist so as to ensure stability in society, not to enforce a moral code. That changes when you begin to look at effective theocracies, and other primitive governmental systems.

Therefore, the existence of laws can not threaten the belief of a person in no objective right or wrong.