With the greatest of respect nailit, you have made a grave error here !
Never, but never engage in conversation with JWs on your doorstep...a complete waste of time. What you need to do is this...tell them you have been "Disfellowshipped"
This is the worse thing that a JW can hear on a doorstep. They will go white as a sheet, reel backwards, turn around and make their way back down your garden path as fast as their little legs will allow them. They have been known to hurdle closed gates faster than Colin Jackson ever did in the Olympics, in their frenzy to get away. Much more importantly, they will never return as your address will be added to their Black List.
For added amusement, you can follow them up to the top of the road, where all JWs gather on a Saturday morning, shouting out DISFELLOWSHIPPED as loudly as possible. Its hard work but you could be saving your local neighbourhood from future visits, and anyway, its great fun ! More fun than secreting a old kipper behind the rear pews in Chapel !