a very common belief these days. revolves mainly around the idea, "what is right for you isn't right for me". denies that there is truth at all. many relativists realize that mathematical truths cannot be disproven, but they still susbscribe to the idea that multiple opposing ideas can exist in the same realm and still produce no conflicts.
hitler thought it was perfectly fine of him to kill millions of people. obviously, he was a relativist. the people he oppressed obviously didn't have the same veiw, and look at what happened. they were killed.