But much of the canonical mainland political belief system is incompatible with rational thought and generally shared moral principles. And mainlanders are obviously not any less rational or moral on most topics.

Mainlanders may not like it to hear it, and I'll even go as far as to say the best strategy for discussing politics with mainlanders is to not directly tell them this, but their political canon is anomalously full of holes that are exposed when explored in any significant depth (yes I've been through this process with mainlanders).