Moral Supremacist

A "Moral supremacist" (noun) is defined as a person who assumes that their moral view on a given topic is inherently more correct than all other moral views without any evidence to back them up.

"Moral supremacist" has a negative connotation due to being characterized by their condescending and/or patronizing attitudes towards all parties that disagree with their worldviews.

Liana was acting like a moral supremacist when berating Nick about his decisions