Passion is a wonderful thing.
When someone is “wrong” about a subject that you care passionately about, it is natural to argue with them and try to “prove” to them that they are wrong.
Mentally step back. Look around. There is always a third person in the room. Even if that third person doesn’t look like they are paying attention; they are.
Are you at a party arguing in a corner? The tone of your voices will reach others. The facial expressions will reach others. What are you saying to those other people?
If this is a subject that you really do care passionately about, and the second person also cares passionately, diametrically-opposite opposite to you, neither one is likely to convince the other to change their mind.
The person’s mind you can change is that third person. The person who is casually observing. The person on the fence who hasn’t yet made up their mind.
Take the time to use and channel your passion to reach that third person to your side. That is the person you need to persuade.
Focus on being pleasant and reasonable sounding. Not argumentative. Don’t be dismissive of the person you are directly disagreeing with.
Use curiosity to counter their points. “I am curious why you feel this way, when …” (h/t to Genie Z. Laborde, Ph.D. )
Your curiosity conveys open-mindedness to that third person. Your curiosity will persuade that third person.