From my understanding, most of the protesters that show up have no intention of changing your beliefs or ideas, but their main goal is to rile someone up enough that they're hit, so they can sue the con or the city, as a previous poster said. I've read that sometimes people like this aren't even religious at all, but spouting religious diatribe is an easy way to get younger con goers agitated, and raises their chance of being able to file a lawsuit. It's best to just stay away from them and ignore them, because that's all they want out of you.