I found the Penn Jillette video interesting. I like all of his stuff pretty much. I do disagree with him when he says that you have to answer the questions of agnosticism and atheism. If you define agnosticism as believing that it's impossible to know whether there is a god, I think you can stop there. I can say that it's impossible to know how and when I will die. I could absolutely deny that I will die in a killer squid attack tomorrow, and I will be right, but if I have established it is impossible to know, why answer the question with anything other than that.