Everything you say here is valid, although I would suspect that it’s not as limited to this particular issue as you suggest. I think the majority of folks don’t tend to really think that hard or often about why they believe what they do.
Perhaps even harder is thinking about what OTHER people are thinking, and why. Most people aren’t bad, or malicious, really towards anyone. And those that are tend to be so out of fear. A lot of sources of conflict, especially with something like racism, stem directly from this kind of fear. In my experience, the best way to combat it is often not to demonize those people, but rather to recognize that they are likely good human beings who are acting in something of a rational manner, but with incomplete information.
I forget where I originally saw it, it may have even been on these forums, but there was a cool article about Daryl Davis, a blues pianist who ended up befriending KKK members. I’ve seen similar things happen (albeit, not with a case as extreme as that, but with homophobic folks who end up softening their stance once they actually interact with normal gay people).
Generally, attacking them for their beliefs just puts them on the defensive. If you assume they’re evil, horrible people… well, they can’t really come around to your side. Because they’re not evil, horrible people. If that’s a major pillar of your argument, then it kind of precludes adoption of it. But if you start with the assumption that they’re decent people (and really, if they’re not, then there’s little point in talking to them anyway) then there’s some hope that you can slowly expose the parts of their experience that cause them to believe certain things, and work on better compartmentalizing them so that they don’t create such large misconceptions about things.
With a case like Daryl Davis, he basically brought down the whole KKK in Maryland, just by befriending a bunch of the members, because while it’s easy to hate an abstract entity like, “a black man”, it’s much harder to hate an ACTUAL person who is more than a one dimensional caricature.
As I said, I’ve seen this with gay people, and Davis’ story highlights it with a black person. I’m not sure exactly how it fits with sexism though, as we generally all have common interactions with women. It may be different because while homophobia or racism often hinges on the assumption that people in those groups are “bad”, sexism isn’t really based on the idea that women are bad. It’s more based on some notion that certain roles and positions within society are simply the “correct” positions for women. That may be harder to expose people to, and get them to accept the sort of change.