Critics of multi-culturalism often mock its proponents for (a) cultural relativism and (b) disrepecting Columbus. The problem, as I've explained before, is that Columbus was a pioneer of slavery and barbarism. The only way to excuse his behavior is to say "Oh, you can't judge Columbus by our standards. In those days, people thought that slavery was OK. Everyone was doing it."
If that excuse makes sense to you, you're a cultural relativist. Change your heroes, or change your meta-ethics!