what features of boston society in 1642 made the puritins actions towards Hester understandable?

I think we need to understand that the Puritan village was pretty isolated and their society insulated from cities and the life outside. Everything within the village was based on Puritan beliefs. It was a Puritan theocracy thus Hester's "sin" would have been most scandalous attracting a lot of interest.

lack of enough info