"The problem is, what is 'reasonable and commonly-held belief'?"
If it is held by lots of well-meaning people who are open to hearing reasonable arguments and potentially changing their mind over time.
If an opinion really only survives by pure belief and faith, then not much will be learned by discussing it.
Take something like trans atheletic competition. A lot of people haven't thought much about it. Maybe they are worried that girls' atheletics will suffer because the top athletes will all be trans (in many sports), which could be discouraging for the lower levels of competition, and basically make them no fun.
If someone comes up with a plan that's still fun and inspiring for everyone, then I think many people will change their minds. But there's no widespread knowledge and consensus on what that might look like, so I'd say people resistent to trans athletics for that reason are still reasonable people.
I'd also like to be clear that pure beliefs can still be "right" and moral, but it's just not worth discussing them because nobody's mind will change based on reason.