I have succeeded a number of times in the past. A small fraction of attempts, but they still matter. There are even people here that were glad when I came back that told me that talking to me changed a lot of how they view the world. Those people also still freely debate me, but they do it with thought and they actually agree with me in some areas they didn't before. :) They can at least see when someone is trying to con them and manipulating them with fear, emotions, and common logical fallacies.
EDIT: And they also teach me new things as well. It isn't other minds that I change. The process also changes my own.