Former preacher Dan Barker debated Cardinal George Pell on 11 March 2010, at Macquarie University. The full video was made available on the university website.
Pell leads with the argument that maths, physics, biology, goodness, truth, and pretty much everything can only be explained in terms of a transcendent mind, inaccessible to empirical study. He does not at any point formalize his argument or attempt to show how an invisible, immaterial, atemporal, non-spatial, all-powerful mind might possibly exist, much less how it is necessary to explain everything that does. Pell manages to sound authoritative and priestly even while failing to make any weighty theological arguments, except for a poorly stated version of universal fine-tuning. He throws around probabilies without trying to explain how they were (badly) computed. In short, the guy rambles. At one point, he says something so ridiculous about evolution that a young woman in the audience bursts out giggling for just a moment before controlling herself. If ever I got to choose which theist to debate, I'd probably choose George Pell.
Barker, by contrast, makes a fairly clear case and manages to pick apart those of his opponent. He leads with a few opening arguments:
1) Evidence of mystery is not evidence for God
2) The purported properties of God are logically incompatible
3) Terms like "spiritual" and "supernatural" are ill-defined and possibly incoherent
4) Theodicy has failed, along with other efforts to meet atheological arguments
5) Religion offers scant moral guidance on the serious ethical questions of the day
6) An externally-imposed purpose of life offers slavery, rather than meaningfulness
Overall, Pell's rebuttal to Barker offers one misconstrual after another of the relevant arguments, while Barker's rebuttals to Pell are mostly spot on.
Honestly, this is one of the more one-sided debates I've seen in which the unbeliever vastly outperforms his opponent. Personally, I have some trouble enjoying one-sided contests, unless the losers are from Texas. Overall, though, this was a reasonably good debate.
Unbeliever rating: 4.5
Believer rating: 2.5
Overall rating: 3.5