If your house is too warm and you're running 20 electric heaters but for some reason think it's something else causing the heat, it'd still pay to turn off some of those heaters to compensate for the external cause since you actually have control over the heaters.

If you really think that anything you say will have any impact on them then maybe it doesn't matter what the cause is as long as you can get them onboard with the solution. The two are inextricably linked so if they're really adamant about this you'll probably not be successful in this endeavour but it's worth a try if you have some faith in them. If they think it's all long term cyclical solar patterns or some other non anthropogenic cause it might be worth pointing out that it's still happening and causing consequences. The trouble will be not implying too heavily as I have in my heaters example, that the solution is obviously linked to the cause, even if it is. Otherwise they will not believe you have common ground.

Nothing. You can’t logic someone out of a position they didn’t use logic to get to in the first place. There’s way more unmotivated and un-mobilized people out there that believe in human caused climate change that are more worth your time and energy.

What if that person think CO2 is good for life?

Trees in Egypt?

I think CO2 is good for life, but cement in cities, deforestation and the heat produce by burninf fuel must be bad.

I don't trust too much the CO2 crisis, we got other pollution like micropastics and eternal chemicals I believe are more serious.

Anyways I still commute by public transport even though I have a company car with petrol, everyone can help.

another one that doesn't get it

Yes for sure, it's not a desert

I showed that to my father. Completely ignored it.
I guess it didn't align with his beliefs.