"Why are Christians so afraid of Subjective Moral Reasoning?"
That's not the arrogance. That's a question that deserves a good answer, and it gets one at the link. No, the arrogance in that snotty little brat's statement was when he asked if we were afraid that people would just start raping and pillaging if they didn't have a book to tell them what to do. He says "I'm not afraid of that, because it's not going to happen."
Say what? Just how historically illiterate do you have to be to say that? And the arrogance to say "That's not going to happen" when not only can it happen, it has happened, all over the world, and in our country.
In any case, go watch the video to hear the response to that question. The person who gives the response is far nicer than I am.