Stay away from debates. Period.
Nearly everywhere I go, I've found that politics/gay rights/abortion/ect type threads bring out the worst in people. Trolling, flaming and all of that mean nasty stuff. On top of that, you'll end up with the rent-a-modders, who hold no position of authority on the forums and decide to berate other members for breaking rules. Forum members get mad at each other for long periods of time, and can really ruin trying to keep a "friendly" feel to the place.
I've never had to deal with that on any site of mine, thank God, but I've seen too many places turn to absolute garbage when "serious discussion" forums pop up. Hence why I've been posting at places where anything of that nature is rarely discussed.