https://en.wikipedia.org/wiki/Deep_canvassing
The idea is basically that if you attack a strong belief head on, the person you’re talking to will reject your arguments instinctively. It’s a natural psychological defense mechanism. No one likes being wrong, particularly about things that are tied to their identity.
Instead of dictating facts, you start a dialogue and ask questions that encourage critical thinking. If you are empathic, patient, and non-threatening, they sometimes (sometimes!) start making realizations on their own that change their opinion.
And as many a good therapist has said, the patient has to want to change.