I don't expect him to beat a professional (and a very successful) debater.
The word we'd need to better define is "beat".
Will WLC appear to win the debate? Likely. Will he appear to overwhelm his opponent? Likely. Will he succeed at framing the debate in a way that suits his position? Overwhelmingly likely.
The debate takes place in front of his home crowd (an Evangelical theological seminary). WLC will gallop his way to "victory" again, methinks.
If you predict that he'll win under every definition of "beat" that you suggest, why do you need your initial disclaimer that the definition matters?
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.