self-righteous
Acting like your morals make you better than others.
Self-righteous describes someone who acts morally superior to others, convinced that they alone know what's right while everyone else is wrong. A self-righteous person doesn't just believe they're correct: they parade their supposed virtue around and look down on anyone who disagrees with them.
Picture a student who recycles their lunch trash and then spends the rest of the day lecturing classmates about how wasteful and careless they are. Or imagine someone who follows every school rule perfectly and constantly points out when others bend even the smallest one, acting shocked and offended instead of helpful. That's self-righteousness in action.
The problem isn't having strong beliefs or doing the right thing. The problem is the attitude: a self-righteous person wears their good behavior like a crown and uses it as a weapon against others. They might be technically correct about an issue, but their smug, judgmental tone makes people tune them out.
When someone calls you self-righteous, they're saying you've crossed the line from confidence into arrogance about your moral choices. The opposite of self-righteousness is humility: recognizing that you don't have all the answers, that others might have valid perspectives, and that being kind matters more than being right.