Yeah like somebody else said, you'd have to challenge their philosophical believes that leads them to hold this opinion first.

And that in turn requires argueing them from a position not based on "I disagree, and my opinion is the correct one", but on philosophical, logical and argumentative flaws in their believe system. Which is not easy to do. At all. It's in fact very hard, made harder by the fact that our brains can see information, actively realize this information is correct and contradicts something we thought of earlier, and yet also discard said information and stick to the existing mental model instead. Meaning that even if you do everything correct, they might go "Yes, that's true" and then nothing happens, out of no ill will.