Yep, I've run into that too. I am in the Cincinnati OH area and we do have people from Appalachia and rural areas that still believe that we are WITCHES! When I get booked at churches some have requested that I don't bring in cards "because cards are the devil's work."
I have also been asked to not mention Harry Potter. Religion and logic are not always compatible.
A lot of it is simple ignorance. People are of the mistaken belief that Playing cards evolved from Tarot cards, which were developed for fortune telling. Fact is I was of this mistaken belief. Turns out that Playing cards have been in existence for a LOT longer than the tarot, and that the tarot came a lot later.
As for Harry Potter. To many churches there is no difference between stories about Witchcraft, and the Occult, even if written as pure entertainment, and Witchcraft itself, or the occult. And it is their belief that Witchcraft exists, and has something to do with Satan. When Wiccans are basically nature lovers and worshipers that pre-dated Christianity.
As I see it the main problem is one of.." If our pastor says it it must be true, if anyone disagrees it's the devil." Kind of hard for them to get any info independant of their denomination since they do not believe in science being " neutral". All one can do is keep them in prayer. ( not trying to be funny )