On the subject of why Darwinists won’t debate, I should add this further caveat: They won’t debate anyone who knows the relevant science. At Why Evolution Is True, Jerry Coyne has some fun recommending a British documentary series for BBC3 TV, Conspiracy Road Trip, that he participated in. He appears in an episode focused on “Creationism.”
Led by an Irish comedian, a group of five British young people who are fairly described as religious fundamentalists — all attractive and earnest but none remotely qualified to try to rebut a trained Darwinian evolutionist — go on a “road trip” to meet and talk with American scientists set to “debunk” their na�ve beliefs.
Coyne reflects:

When I was asked to participate, I replied there wasn’t a snowball’s chance in hell of real young-earth creationists coming around to Darwinism, but I went along for the fun of it.
My assigned task was to debunk the myth of Noah’s Ark, which I was supposed to do while floating on a boat on Lake Powell.

In his segment, Coyne talks about the limits of wooden boatbuilding and the burning question of what, if Noah had to put all the animals on the ark, they did with the whales? The group of creationists argue back for the most part inarticulately and one young woman, JoJo, who found religion when she was ill with cancer, flees in tears.
It’s a hopeless matchup, of course, and cruel, all done for laughs at the expense of some poor innocents. These Brits believe in a literal interpretation of the Bible, but they are not the kind of YEC advocates who come equipped with at least serious-sounding arguments. There’s no shortage of the latter, but the producers clearly sought out people who are little more advanced in their views than children, seemingly pulled off the street at random. This is simply bullying.
Would Coyne ever agree to a BBC-televised engagement with appropriately chosen scientific opponents from the intelligent-design community — not on whales in the ark but on the subject of his own book, the sufficiency of Darwinian processes to produce the wonders of life? You can be sure not.
So why not go all the way and debate actual children, “for the fun of it”? Put Professor Coyne of the University of Chicago up against a 5-year-old. I think one of our twin boys would be willing to take a day off from kindergarten for that purpose if he were paid in relevant currency (candy or cookies).
Then you’d really see Dr. Coyne in triumph.