Seems you have missed my point. Please define litmus test, this may help.
But yes, a person’s reality is truly comprised of what they wholeheartedly believe. It quite literally is their reality.
Discussion
If you want to test individuals knowledge of economics: ask what he thinks about bitcoin
If you want to test individuals basic abilities to think: ask what he thinks about rusians genocidal war against Ukraine
As simple as that. Maybe litmus test is not the best phrase here, but this is what we’ve used at school to test stuff