Relativism is embedded into our culture. I even find many Catholics who support similiar views! I wrote about its effects catholicrebel.blogspot.com/2013/05/relatively-absolute-part-2.html but it is still difficult to convince people. What do you find are the BEST arguments that are practical and work in a debate?
Jesus answered, “My kingdom is not of this world. If my kingdom were of this world, my servants would have been fighting, that I might not be delivered over to the Jews. But my kingdom is not from the world.” John 18:36
This website of Peter Kreeft should be very helpful.
**The idea of relativism is so self defeating. Deep down, no one is a relativist. Everyone thinks that something is wrong. If it is a relativist, then ask them by what authority do they think it’s wrong. If I think it’s right, then it has to be for me, regardless of whether or not the relativist likes what I do or not. Then add to the fact that the relativist is imposing his/her will on me when they think something is wrong while I think something is right. Therefore, it’s not relative because they care enough to “impose” their will on me regarding an issue. **
Is it true that there exists no objective truth? Note the contradiction in the claims of relativists. In a debate it is best to let them “put their foot in their mouth” first by letting them makes this claim then ask, as if for clarification, “so what you are saying is that it is true that truth doesn’t exist?”. If they don’t get it immediately help them see the contradiction for themselves: it cannot be TRUE that TRUTH doesn’t exist.
A slight problem is that no one is really a self-described relativist, and denials of universal truth are often implicit. People tend to think that they know what is true and will only express relativistic tendencies on subjects where it is convenient (ie. morality). For this reason the classic “the statement that there is no objective truth is an objective statement” refutation really has very little application in actual dialogue. Really, I think the only thing to do is point out logical inconsistencies when they do crop up.