I personally use debates to learn about the viewpoints of other people, not to change theirs. Some religious folks are not stupid. Such as edwardfeser.blogspot.com sure, they are just smart post-hoc rationalizations and essentially irrational in the willing-to-change-mind-in-face-of-evidence sense, but interesting ones. They teach a lot about psychology. I may know better what is true, but they may know a lot better what feels good to believe for the human brain. I am also fascinated how much logical consistency can be achieved without the whole thing being real. Often very much.