My intuition would be that nobody jumps the fence as a result of these sorts of things. They were either the sort who would have agreed with the conclusion without any argument anyway, or they will do mental gymnastics of all kinds in order to avoid believing the conclusion. But, having never really been religious, I'm probably wrong about that.
An interesting little Flash-like video on "openmindedness" by someone named QualiaSoup (hopefully ironically).
Does anyone know how much effort is required to produce this sort of video, perhaps from a script? We need at least another thousand of these.