Cult Control

Most of us have had this experience. Your doorbell rings and you open your door to find a small clutch of people, looking earnestly at you. They ask you if you read the Bible or if you would like to pray with them. Yes, I am talking about the religious cults whose members go door-to-door, trying their best to benight others into their own narrow minded beliefs. Some came around here just yesterday.
What to do?
Of course, the easiest thing to do is simply to say, "Go bugger off!" and slam the door in their faces. This is the "classic approach". It would be better if you didn't have to actually say anything, but simply have a can of spray "Cult-B-Gon" that you could dispense in their direction, sending them fleeing into the street.
The downside to these straightforward techniques, however, is the bad taste of dissatisfaction it leaves in your mouth. Rejection only makes the cult people stronger as they probably believe they get brownie points in heaven for "suffering" in the name of their religion.
Much better would be to have them leave of their own accord.
One solution was offered by a former English teacher in this area. His idea was to prepare a white lab coat and a large pair of calipers near your front door. When the cult members would come, you would don the lab coat and invite them in. Once inside, you would ask them to remain very still before they could begin their spiel about their religion. Using the calipers, you would measure each of their heads from side to side, concluding with singling out one of them, "You can stay, the rest of you must go." The teacher figured they would all leave on their own, not gaining any brownie points for their "suffering".
Another solution that didn't require any advance preparation was once again to invite them in. When they begin their presentation, you interrupt them and ask, "Does your god glow in the dark?" Undoubtedly they would be perplexed by your question, but answer in the negative. With a snort, you further query, "Well, surely your god's eggs glow in the dark then, don't they?" Assuming you have some sort of mental illness, they would probably leave on their own accord, once again, gaining no brownie points for their efforts.
The third technique is to preempt them in their presentation. After inviting them in, you ask for them to quickly join hands with you in prayer. You pray loudly to some god that is unfamiliar to anyone – say, Zorbac – calling on his (or her) blessing for the poor misguided folk who have been brought to your doorstep by providence and his (or her) divine intervention. The visitors will become very uncomfortable and leave on their own account when they discover how committed you are to your beliefs and how unwilling to let them get a word in edgewise.
I am sure there are other equally fun ways to deal with the pesky religious cultists. If you have any ideas, please let me know!