Two kinds of relativism
The fundamental divide between the relativism I affirm and the relativism I oppose lies in the conclusions drawn from the conditionedness of all thought. I interpret this to mean that all apprehension of the world is perspectival, fragmentary, and in some measure distorted. To me this means that the first step in the improvement of thinking is awareness of these limitations, the examination of some of the conditions shaping thought, and attention to what others see from different standpoints. This makes possible revision of the initial apprehension. Of course, the revising is also conditioned. There is no overcoming of conditionedness, but there is a movement toward less fragmentary and less distorted perceptions.
So each of us has a partial view of the world that is informed by our own experiences. My experiences of the world are different than yours. I have my own predjudices and biases, which cloud my view of the world. As Paul says "Now we see through a glass darkly." But I can overcome these biases by truely listening to those around me. For example, I had a friend in High School who was Native American. I would not have understood the negative effects of European immigration, if it weren't for her. Of course I will never be able to get to the point where my view of this world is unobstructed.
The other interpretation of this situation emphasizes that not only does each way of apprehending the world express the given conditions, but every reason that can be provided in favor of one or another apprehension presupposes the standpoint of that apprehension. The result can be called "conceptual relativism." For the conceptual relativist, reflection necessarily occurs within a given frame of reference, and there is no way to bridge the chasms that lie between alternative systems of concepts.
This view is very pessimistic and I think the functional difference is one of optimism and pessimism. The second view is very pessimistic about our ability to even talk to others about the world.
Such a view can have positive effects. It works against cultural arrogance and imperialism, encouraging instead mutual tolerance....
Nevertheless, the belief that there is finally no justification for one's ideas tends to weaken the hold of those ideas and to inhibit acting upon them when such action is costly. The belief that those who oppose the direction one favors are equally justified and unjustified in their opposition, that there is no court of appeal beyond the sheer difference, reduces one's incentive to press for public action expressive of one's views.
So the second view leads to apathy and is the view most often demonized in the conservative Christian literature. And while they do have a point, there are other responses that would be more helpful.