I just got to practice the lesson Beacs taught me - I was nice to the Mormons who came to my door, told them the message wasn't for me but I respected their choice to live their convictions, and sent them on their way with two bottles of nice cold water.
I must admit it's a little easier when they're two 19yo, blond-haired, blue-eyed little hunklettes. I fear my good deeds are somewhat mitigated by what goes through my mind in these scenarios.
Oh, well - I'm obviously on the express line to Hell, anyway! They don't need to know the little fantasy I'm having of being the witch in the forest with Hansel & Hansel showing up at my door. "Want some candy, little boys?"