Why are writers viewed as threat to the state, debate authors

Should writing be viewed as a public or private act? What is the dire need to ban books and imprison or persecute writers? Why are words considered to be such potent political weapons? How can writers be a threat to the state?
Salman Rushdie still draws criticism for 'The Satanic Verses', published over 20 years ago. The ugly scenes witnessed at Kolkata Book Fair preventing the release of Taslima Nasrin's new book Nirbashan, accusing her of insulting Islam were a reminder of the 'virtual' freedom of expression.
Despite being a democratic country boasting of 'freedom of speech', why do we still have an elaborate history of literary censorship?

While the western nations were celebrated the 'Banned Books Week' recently, authors here debated to find answers to the above questions.
"There is no doubt about the fact that writing is viewed as an active political engagement and to some extent it is rightly viewed. But why politics has to effect an author's work and ultimately his life?," says novelist and short story writer, Mridula Koshy.
Be it creative writing, politically motivated or anti political, there need not be an intentional agenda always. Every transaction is different, what matters to authors more is that celebrated feeling of writing, she says.