What did Hawthorne think was the true evil in The Scarlet Letter?
Hypocrisy. What is so fascinating about this book is the way in which the authorial voice clearly sees Hester Prynne as a victim, whereas based on the views of her own time, it was she who committed evil, and she who deserved whatever punishment she received. Let us remember that she could have easily had Pearl taken away from her because of the way the Puritans thought of Hester as being "evil." However, if we look very carefully at the Puritan society that Hawthorne describes, the true evil in it is not poor Hester and her act of adultery, but actually the way that Puritan society treated such open examples of sin as being so evil whilst they quite happily practised various evils of their own behind closed doors or even in full view of everyone. Consider Governor Bellingham's house, which is described as being a beautiful, luxurious, state-of-the-art building:
The brilliancy might have befitted Aladdin's palace rather than the mansion of a grave old Puritan ruler.
Although Hawthorne never targets anybody openly, the fact that Governor Bellingham lives in such opulence whilst openly being a Puritan, somebody that stressed simplicity, shows a latent hypocrisy that the whole town models. This is the true sin of society that Hawthorne seeks to expose.