Cách sử dụng
The expression "preach to the converted" means to talk to people who already believe in what you are saying, which is unnecessary as they already agree with you. It is often used to describe situations where someone is trying to convince or persuade others who already hold the same opinion or belief. For example, if you are trying to convince your vegetarian friend to stop eating meat, but they are already a lifelong vegetarian, you would be "preaching to the converted".