How can I argue against the argument: "relativism" is in itself another "centrism"?

Question

To elaborate, one argument against cultural relativism is that the idea itself is another form of ethnocentrism. Because apparently, cultural relativism puts itself in a higher moral ground than ethnocentrism.

So for example, consider this argument by Timothy Keller, who writes in his "The Reason for God":

Many say that it is ethnocentric to claim that our religion is superior to others. Yet isn't that very statement ethnocentric? Most non-Western cultures have no problem saying that their culture and religion is best. The idea that it is wrong to do so is deeply rooted in Western traditions of self-criticism and individualism.

So if I were to follow this reasoning I find this statement to be also problematic.

Don't judge me.

Because I am implying that it is bad to judge, therefore I have judged him.

But I don't think relativists would have problems with those kind of statements. And frankly, I find the entire argument against relativism above to be quite absurd, but I kinda don't know as to why.

Answer 1

Many say that it is ethnocentric to claim that our religion is superior to others. Yet isn't that very statement ethnocentric?

No. That statement by itself is not judging a culture based on the standards of the speakers culture, which is the definition of ethnocentrism.

The idea that it is wrong to do so is deeply rooted in Western traditions of self-criticism and individualism.

So what Keller is really getting at is countering the following argument:

P1. Ethnocentrism is wrong.

P2. It is ethnocentric to claim a religion is superior to others.

C. It is wrong to claim a religion is superior to others.

by making the following argument:

P1. Ethnocentrism is wrong.

P2. It is ethnocentric to claim that claiming one religion is superior to another is wrong.

C. It is wrong to claim that claiming one religion is superior to another is wrong.

If you really want to challenge the validity of this argument from the relativist viewpoint Keller is putting down, you'd have to attack premise 2.

But before going down that rabbit hole, perhaps a better question to ask yourself would be, do you adhere to the definition of cultural relativism that Keller purports in his book?

See: https://en.wikipedia.org/wiki/Cultural_relativism#Comparison_to_moral_relativism for Clyde Kluckhohn's statement on what cultural relativism is and is not.
If you consider yourself a cultural relativist in the sense that you would not condemn the founding fathers for owning slaves because you take into consideration the society they lived in, while still maintaining that slavery is morally wrong, Keller's argument does not really apply to you, and should be viewed more as a strawman. However, if you take the stance that "culture x practices slavery, but I can't say they're wrong for doing so because everything is relative" then as I mentioned before, you would have to address the 2nd premise of the argument.