You can infact have a right/wrong opinion.
For example...
If it is your opinion that eating babys is morally right.. then you are wrong.
There are two points of view on the matter of opinions... the first is this- assume everyone did/believed your view to be correct... would that be good or bad. example- killing people/lying. If everyone killed each other the world would be thrown into chaos, or if everyone lied then no one could trust anyone else..
However the counter to this argument is- The best for the most.. therefore one could argue that killing is just when it benifits all.. when normally killing would be wrong. therefore killing Hitler wouldn't be considered bad due to it's positive effects on so many people...
This is really a question of Tolerance Vs. Acceptance. Tolerance means that i tolerate your idea.. it may be wrong, but it's cool that you have it. Acceptance means that every idea has equal "rightness" and that everyone can have their own opinion, and that everyone is equally right. This is manytimes what you are "taught" in public schools, and many people when speaking on the taboo subject of religion.. not everyone can be right.. deal with it.
Good Day Sirs.