As the president of an atheist / skeptical organization I've occasionally been invited to debate true believers. I've accepted a couple of those in the past, but declined the last invite I've received.
I've come to the realization that debate is merely a sport.
Don't get me wrong - sports are fine. Lots of Americans go crazy over their favorite football or basketball team. And although I'm not usually interested in sports I can spend a pleasant afternoon watching minor-league baseball at the local stadium.
Debates are much like a boxing match. Two opponents duking it out with arguments instead of fists. And like boxing it has very little correlation with finding out what is true or not, outside of who is better at the sport.
In a boxing match being smart about the sport is great, but might not be enough against someone who is quicker and more physically fit. In a debate the more intelligent opponent may be defeated by someone who quickly throws out lots of arguments in a glib, but engaging manner.
This is a terrible way to determine what is true.
Don't get me wrong - debates can be fun to watch or participate in as long as you realize that they ultimately don't have any bearing on what is true. And it is exactly this reason why I decline debates - because religious people take a debate "win" as an affirmation that their position is true.
Equating the winning of a debate with truth is so obviously a fallacy that I'm surprised that no one seems to have given this fallacy it's own name.
As I said, debates can be fun. But in order to remove some of the advantages that debate tactics confer, I prefer to debate only in writing, in a forum that all can see and comment upon. It's easy to make a claim in a spoken debate that an opponent will not be able to verify as true or false. But in a written debate, with a day between responses, it is possible for a debater to unpack his opponent's claim and demonstrate it to be false.
In this, a written debate is closer to the process used in peer review. But not close enough. Ultimately even this sort of debate is not very useful in finding out what is true. Although perhaps it may be useful in determining areas that warrant further investigation.