Oooooh Larc, this is hilarious!! Good luck in trying to keep a straight face during your "bible study" LOL!
One thing I would definitely try though, is when they start in on how Jesus "returned" in 1914 and the insane explantion they give on how they come to this conclusion, just look at them shocked and say "Uh, the city of Jerusalem was destroyed in 586 BCE......where on earth did you get 607 BCE from?" heh-heh-heh-heh............make sure you've got some stuff to back up your claim..........their freakin' heads will have spun around by the time they leave.........the implications after all, are too enormous for them to ignore......