The main idea of the passage is why they is the first two states to choose between union and South they couldn't decide so that's why they made a civil war
Assuming that this is referring to the same passage that was posted before with this question, the editorial writer's main point is that "The mayor and city council have made a serious mistake in selecting a site for a new community theater" since he expresses this more than once.
Purpose of a Thesis Statement. A thesis statement is usually the last sentence of the first paragraph of a composition. It states the topic of the paper and the argument the author will make about the topic.