This was mentioned at the end of the article:

Calvin said on another occasion that it is a blasphemy against the Holy Spirit to deny that pagan writers like Plato wrote many things that are true and helpful.

Hmmm... Is it possible that dissent against J.K. Rowling's writing and denying they serve any good blasphemes the Holy Spirit? And no, I'm not trying to be a smart-alec. I mean, some people seem ready to burn her books.

My kids wouldn't like Harry Potter anway; not enough killing.