I remember a few months ago a couple of people (I think they were Jehovah's Witnesses) came to my door, and started talking about getting sick. They asked if I knew why people got sick, and said it was because our bodies were imperfect due to sin etc etc etc. I, while hardly as well versed in immunology and the biology of disease, told them that viruses spread and adapt due to evolution and so on. I was cordial, but frank about my worldview. Naturally after they left and I had ruminated on the topic for awhile, I came up with a couple things I could have said, but that's life.
I really enjoy discussing religion, and relish just about any opportunity I get to do so.