First sentence of Anthem

"It is a sin to write this" (17).

Ayn Rand begins her novella Anthem with the sentence above.  To me, when I first read this I immediately asked, "What sin? What is "this""?  This opening sentence also made me question if the narrator was speaking to me, the reader, or if the narrator is writing to a different audience inside the story. The key word the author includes here is "sin," but I know from Rand's biography that she was not a religious person; in fact, she deeply abhorred religion and instead favored reason above all else.  "Sin" here suggests that this world in Anthem has some laws or controls over what people can write, if they can write at all.  This opening sentence seems fitting for the beginning of a dystopia because I am predicting a controlling society where individuals cannot express themselves.  What is the narrator writing, and will he get caught? What is the consequence for the sin of writing?