Usually I point to the Mezuzah on the door (which they should have seen); if that doesn't work I tell them that I am Jewish and not interested; if that still doesn't work, I sweetly but firmly say, "Please don't make me be rude by closing the door while you are talking." Most usually works.

Mrs. John had a near evangelical experience when a lady in her art class kept pressing Messianic Judaism tracts on her. When she demurred, the lady decided not to be be her friend any longer.

A couple of weeks ago in my cardiac rehab session, a born again minister was telling me that his congregants were going to learn Jewish songs & dances from four [count 'em, 4] Jews for Jesus. I allowed as we had a name for Jews for Jesus in my circle...'Christian'. "Mm, yes." he said, and quickly moved on to the next apparatus.