Some people just like to argue; and some are really good at it! Consider using this propensity to your advantage when preparing for lessons that are conducive to strong arguments and opinions. Think about two different well-spoken individuals in your class who would be willing to prepare beforehand for a debate-style presentation during your class.
It should be emphasized to the participants (and maybe even the class) that the point of this debate is not to destroy faith, but to enable the class to seriously consider both pros and cons of whatever the issue is, even though one side of the argument might seem to be heretical - that real, sound faith does not have all the answers, that ambiguity is okay, and that such questions can bring us closer to God rather than to draw us away. (It is better than a ball team’s weaknesses be exposed on the practice field than during a competition.)