How does Chesterton define “orthodoxy,” and what examples does he give to illustrate this definition?

The reality of paradox is a central theme to the book’s overall message, but in what way(s) is paradox used in Chesterton’s own writing as a rhetorical device? Support your answer with evidence from the text.

Why does Chesterton hold to the viewpoint that only Christianity can provide a fixed and eternal ideal for human beings to judge life by? What evidence does he give for this idea?