Today , we talk about a type of shared belief . Often in our lives , we come together with others because of a shared belief or purpose . That group can sometimes be called a choir . A choir can describe a group of instruments of the same type , for example a brass choir . A choir can be used to describe an organized group of persons or things . For example , many rich , famous people travel with a choir of assistants . A choir is also a group of organized singers in a church . This is the most common definition . For today's expression , we will focus on the church choir . The expression is “preaching to the choir .” Church leaders preach . You can preach about something you believe to be good or necessary . However , people who preach to others , speak to them in an annoying way about the right way to behave . They may sound as if they think they know better . And books that try to teach a moral lesson could be criticized for being too preachy . But now , let's get back to our expression “preaching to the choir .” So , I am not looking to convince them . Perhaps , I am just looking to feel good about my idea . When you preach to the choir , you are sharing your opinion with people who already agree with you . They are already on your side . You don't need to convince them . So , sometimes it means you are wasting your breath , like in this example . You know , we need a park in our neighborhood . I couldn't agree more . The empty property at the end of the street would be perfect . And it's near the woods . So , it'll be very quiet . You don't have to sell me on your idea . I brought up that same idea years ago . It would be great not just for the kids , but for everyone ! It could be a gathering place and a place for community activities . I already know all this ! Now , you're just preaching to the choir . What you need to do is to talk to all the other neighbors on this street and get them on board . A few were against the idea years ago . Here is another example . We're already doing that .”