not wanting or allowing people from minorities (= small groups that are different from the rest of society because of their race or religion) to be accepted as part of a country or society

This argument is, in fact, a form of anti-assimilation rhetoric. 事实上，这种说法是一种反同化言论。

I realized that there was this whole anti-assimilation thing going on. 我意识到这一系列反同化的事情正在发生。