I guess if you truly want to refine your thinking skills and ability to debate religion, ask some specific questions. What parts of the movie did you feel inadequate to address? From what I gather from the trailer, the movie was just littered with fallacies and misrepresentations, so just bring up whatever issues you see and others can help you.
Even if the open windows of science at first make us shiver after the cozy indoor warmth of traditional humanizing myths, in the end the fresh air brings vigor, and the great spaces have a splendor of their own - Bertrand Russell