As a Pagan I would like to say that some people do get curious about witchcraft because of things like Harry Potter... but most Pagans are well aware of the books/movies/tv shows that might foster this curiousity and we are quick to set the record straight that 'real magic' is nothing like what they've seen or read in fictional books etc. and most people, once they find out that, forget about 'real witchcraft' all together.

I'd also like to point out that many people have been 'leaving' the Christian Church for many years now. Long before HP ever came out. And also Pagans/Wiccans DO NOT worship the devil. Most don't believe in such a creature.