Or, if the protagonist’s needs aren’t being met because they’ve just survived an apocalypse, the theme might be “the environment” or “man vs. nature.”
In other words, theme describes the central ideas that a piece of writing explores. And, because a story is propelled by conflict, theme and conflict are closely intertwined. If the protagonist’s needs are jeopardized because of the government, the theme might be “justice” or “power & corruption.” Or, if the protagonist’s needs aren’t being met because they’ve just survived an apocalypse, the theme might be “the environment” or “man vs. nature.”