I tried "I don't speak Japanese" when I was visited by Japanese Jehova's Witnesses in Japan and they came back with copies of Watchtower in English.

I don't fancy inviting them in. What could be more boring than talking to these people?...

"Why do you believe in god?"
"Because god told me to in the Bible."
"What makes you think the Bible is the word of god?"
"The Bible says so."
"That's stupid."
"No. It's faith."
"No. It's stupid."
"God moves in mysterious ways."
"You mean like in Genesis, 19, where two angels come to visit a bloke called Lot; the men of the village ask Lot to hand them over so they can rape them; Lot refuses but offers to let them rape his teenage daughters instead; the villagers refuse, so the angels blind some of them; God is displeased (because the angels are male and he only approves of females being raped, not males) so he decides to slaughter everyone in the village in a giant fireball; the angels encourage Lot and his family to run away, which they do, but when Lot's wife disobeys the angels' instructions to not look back while the village is turned to ashes, God kills her, turning her into a pillar of salt?"
"Yes, that's right."
"Right, I think it's time I cut your hand off with this meat cleaver."
"You what?"
"It's all right. God told me to do it. He moves in mysterious ways, you know."
"Oh, okay, well if God told you to do it then it must be good. Hack away..."

Yawn...that would bore me to tears.