Shamist
An extreme moralist. A person or group of people (shamists) who shame others from a false position of moral superiority rooted in their personal beliefs, often religious or cultural.
I was walking through the mall this evening when I saw a mother breast feeding her child. Nothing was visible, she was not bothering anyone. All of a sudden this shamist walks over and tells her to leave because they were uncomfortable with her doing that in public. They told her she should be ashamed of herself.