be preaching to the converted

be preaching to the converted

To be trying to convince someone about something that they already support or understand. You're preaching to the converted here—we all have kids and understand how busy life with kids is.
See also: convert, preach

be preaching to the converted

If someone is preaching to the converted, they are presenting an opinion or argument to people who already agree with them. You're wasting your time preaching to the converted. In any case the film was, by and large, preaching to the converted. Note: The converted are people who have converted, or changed their religious beliefs. Preaching is the activity of telling people about a religion.
See also: convert, preach
References in periodicals archive ?
While Bright does seem to be preaching to the converted (Jerry Falwell is not likely to be first in line to buy a copy of the book), in fact no one is completely "converted.