sanctimonious

Adjective C1 – Advanced

Making a show of being morally superior to other people in a way that feels false or self-satisfied.

"His sanctimonious lecture about honesty rang hollow, given that he'd lied about it himself the week before."

'Sanctimonious' is almost always negative and implies the person's moral display is fake or exaggerated, unlike a neutral word such as 'devout.'

Synonyms

self-righteous holier-than-thou