There is no god in harry potter. The overriding theme is that you become what you choose to. That means there is no gods will. in harrypotter, no one worships god, there is no heaven or hell... yet the good triumphs over evil... that means god is not required
Harry potter is a childrens story. such stories live for ever, and continue to amaze, entertain, and educate children. for eg Jataka tales, Panchatantra, sindbad the sailor, alibaba & 40 thieves, alladin.. these tales are thousands of years old and still alive.. Probably Harry potter will also live long and eradicate their superstitions.
