Here's a tried and true weapon for deflecting the issue:
Elder: Mary, do you consider yourself one of Jehovah's Witnesses?
Mary: Well, I don't think I am, but Roberta is.
Elder: Uh, who's Roberta?
Mary: She's one of my multiple-personalities. She's been studying with me ever since I got put on death-row.
(Elder makes a b-line for the door............bye-bye! Don't let the door hit you on the way out!)