Interesting responses and the funny thing is that put together they sound an awful lot like what was going through my mind at the time. I think in retrospect the thing that I am fighting more than anything is that it touched every single stereotype button you can imagine for that flight.....SW....."cracker accents"......they were discussing "the ministry" for a while as well, etc.
After a while I was just becoming more incredulous rather than angry. To make it clear this topic of conversation was decidedly two way, both the man and the woman wanted to participate. If it would have gotten that they were making truly derogatory or hurtful remarks (so and so's all need to die, etc) I would like to think that I would have said something on the spot. What was truly funny when I think about it is that they were also every once in a while throwing in the classic Seinfeld "not that there's anything wrong with that" sentiments. It was more like each was trying to impress the other that they could clearly identify "one of them".
Although I didn't end up using a good one liner on them, I have in the past. First trip to Salt Lake City and I really wanted to see the Temple Complex. You have to go on a free tour to do it and I wasn't really up to dealing with the "conversion thing" during the whole thing as I really only wanted to look at the buildings, etc. Tour guides for the small group I ended up with end up being these absolutely adorable young mormon women in their late teens / early 20s and sure enough as we're walking towards the building the choir performs in she walks up next to me and chats me up, where am I from, etc. Then she hits me with "so do you think it's possible that our Lord Jesus Christ came to the new world after his resurrection and appeared to the natives?" Without hesitating I said, "I don't know but I think my BF probably would." She got this startled look on her face and for the rest of the tour I was left alone!