sanctimonious

Merriam-Webster’s defines sanctimonious as “displaying high-mindedness with intent to impress.”
It’s a holier-than-thou thing with an etymological connection to the “holy” part.

People these days who might be thought of as sanctimonious are rarely puffing up their religious piety for the sake of show (although there are some). But that’s definitely where the word came from (pretending to be very holy or pious)

At first though it wasn’t a bad thing to be sanctimonious. This is because sanctimonious is one of those words that started out good and then turned bad. People who were really and truly thought well of based on their devotion to religion were the first to be called sanctimonious. But the word must have quickly been used mockingly for those who were just putting it on, because people rapidly stopped using sanctimonious as a compliment.

Both senses emerged from the verbal into the written within a year of each around 1600, but the complimentary sense was forgotten within 200 years while our current negative sense lives on.

Can also mean = Making a show of being morally superior to other people.

My dad was a prime example !!

Me : Why ......?

Dad: Because I say so.......