Merriam-Webster defines "preaching to the choir" as "to speak for or against something to people who already agree with one's opinions." And their example of using the phrase in a sentence (or two) is, "The speeches he makes to his supporters won't win him any more votes. He's just preaching to the choir."
But this way of thinking, that "preaching to the choir" is basically useless, is completely "backwards," according to political commentator Leigh McGowan, aka Politics Girl. Fox "News" doesn't worry about preaching to the choir, she says, and look where it's gotten them. "This idea that I shouldn't bother to do any of this if I'm not changing the minds of brainwashed, MAGA evangelicals is so deeply backwards. How do you think they got like that? What do you think Tucker Carlson and Rush and Ben Shapiro and The Five are doing if not "preaching to the choir"? They're filling up the whole church with like-minded people and doubling down on their message," she says.
"I'd argue one of the Democrats' biggest problems is that we don't reach out to our people enough," she continues. "We don't make it exciting to join the choir and hear the message and show up every week. … We need to fill our church. It's only the passion of our base that is holding back autocracy at this point. So we're going to need as many people as possible in those pews!"