Cultural relativism is a refinement of cultural absolutism, in order better to deal with the empirically undeniable discrepancies in moral judgements between different individuals and groups. Basically:

Cultural absolutism: us good, them evil.

Cultural relativism: under these social circumstances, those moral preferences are likely to emerge.

Clearly, the former is easier to handle than the latter, which has advantages in some situations.

>Cultural absolutism: us good, them evil.

>Cultural relativism: under these social circumstances, those moral preferences are likely to emerge.

This strikes me as the fallacy of the excluded middle.

Many people believe one culture is better than another without necessarily believing one is entirely good/without fault and the other is entirely bad.

The problem with cultural relativism as I understand it is that it denies me the right to make any judgement. I mean, you phrased as opposing "they're bad" but in practice it opposes "they're worse"

    fallacy of the excluded middle.

I'd say I was being terse, and trying to boild down the matter to its essence, so as to enable clear thinking. Naturally, positions we hold are more complex.

   it denies me the right to make any judgement.

I don't think a mature cultural relativist denies you any judgements, it's more an invitation to investigate more nuanced positions.

You believe in moral absolutes? What is the ultimate good, then? And who is born evil?

Yes, I believe in moral absolutes in actions and deeds, not in people. I don't believe anyone is born evil.

I see. So which cultures are good, which are evil?