If you want to prevent meaningful dialogue from taking place, here's a tip: Apply categories. Get at least one of the people involved to think of their position as the "conservative" or "liberal" position. Better yet, get them to start thinking of themselves as "liberal" or "conservative". This works in virtually any setting (theology, politics, etc), and really only requires one of the dialogue partners to apply the labels to be effective.
If preventing meaningful dialogue doesn't go far enough for you, here's another tip: Polarize the argument. Convince at least one of the people involved to define their category so narrowly that to differ on any point, or even to question any point places one in the opposite category. Cultivate an us/them mentality. Make it about "winning", or even about "not letting the other win", more than substance. Cultivate the idea in an individual (or group) that the position they currently hold is the one that any sensible person would naturally come to if they would only be objective about the matter. Once a person becomes convinced of the obviousness of their own position, they will naturally assume that anyone who disagrees with this position is obviously stupid, or an evil person who is intentionally misleading others.
Make sure that these categories get reinforced frequently, perhaps by employing overbearing media personalities who can boldly and consistently articulate the intelligence and rightness of their own position. Note: these personalities should never be self-critical, never recognize anything good in the other, and should only have anything resembling a sense of humor in reference to those they seek to ridicule (they should never be self-deprecating).
Follow these steps, my friends, and I guarantee that you will prevent any empathy, understanding, and progress. Remember, you don't have to win the debate to maintain the status quo. You just have to apply categories and polarize the argument.
A few warnings though. For this to work, you must avoid the following at all costs:
- Asking questions
- Engaging with the questions of others
- Listening to the best articulations of other perspectives
- The idea that there even can legitimately be other perspectives
- spending time with others who are unlike you
- Anything beyond a Gospel of "sin-management"