bah. there are so many more FUN ways to deal with it. its so much more fun to come out with a cigar hanging out my mouth, beer in hand, tattoos and piercings showing, some offensive shirt on, and explain to them that they're not equipped to witness. they have their 1 or 2 select verses, usually written down, and from there they don't know what to say, usually coming back to their small selection of verses.
questioning them usually shows that they are quite ignorant of the religion that they preach.. at least around here. i end up telling them to go study, then come back to me before going out again. so far, only one was serious enough to do just that.
I have had to occasionally lean out the window and call, "Honey, come inside and leave the nice people alone!"
They don't come back.
A friend of mine hauls out her Book of Common Prayer and tries to convert them to the Episcopal Church (or at least she used to before they got so crazy.)
I used to answer the door partially clothed, holding a handle of whiskey, and a cat in the other hand, etc.. I'd wipe my mouth and pretend to be interupted having sex. The more outlandish the funnier it was. What a hoot! The looks I'd get would have me laughing so hard my ribs would hurt and I'd get the hiccups. Kind of like reverse trick or treating.
Lately I guess I've mellowed out a bit. The folks that came to my house lately were respectful and polite, so I've just thanked them and sent them on their way. They seem to mean well, and want to help me in their own way.
So far they've respected the no trespassing sign.