Pell was perfectly awful here, but Richard could perhaps refine his explanation of the difference between agnosticism and atheism by emulating Penn Jillette in this very entertaining video from, believe it or not, Faux News:

http://www.youtube.com/watch?v=OQsOZopBBkQ&feature=related

Essentially, agnosticism is a statement that one simply doesn't know whether or not these nebulously-defined entities like gods can exist, while atheism is a description of one's opinion - of the moment and subject to change - that they very probably don't. Believers love to call this dogmatism, which of course it isn't because believers don't like the true meaning of the word.

Penn appears at 4:40 after some amusing banter among the regulars, endurable because it isn't the least bit political for a change.