One of the more useful documents I’ve found on the topic of cultural relativism is this one, by Wood:

In philosophy courses I often encounter people who say things like this: “What anyone believes is true for that person. What you believe is true for you, what I believe is true for me.” The view expressed in such statements is usually called “relativism”. This view denies that there is any such thing as absolute truth and claims that all truth is relative to the person who believes it.

Read the whole article here, or download as Word document here.