Autobiography
The Confessions is like an autobiography on steroids. We've got all the usual ingredients for an autobiography: a first-person narrator telling us his exciting life story. But Confessions focuses on the most personal, shameful, and embarrassing aspects of his life; while this kind of juicy, tell-all autobiography may be more commonplace nowadays, it was pretty ground-breaking in Augustine's time.
When reading some autobiographies, we can learn about the kind of person our narrator is by looking at what they choose to leave out. Augustine chooses to focus on the bad bits of his life—the parts that other people would definitely want to leave out. That's what makes the Confessions confessional, after all. On that note, "confessions" are almost always autobiographies, whether they are real or fictional; see our What's Up with the Title? section for more.
Philosophical Literature
Though the Confessions has a plot, it's also full of philosophical commentary. You can think of this book like a director's cut of a movie, where the director tells you all about what's going on as it's happening. Of course, Augustine's incessant philosophizing focuses on Christian theology. Hm. Do you think that all religious works are philosophical?
Well, what makes the Confessions a particularly philosophical work is that it asks questions about Christian thought, being, ways of accounting for the universe, good and evil, the substance of God… you get the idea. It's about religion, but it's also an exploration of religion(s). Augustine engages in a lot of thought experiments, as well as life experiments, to try to figure out what happens when you apply Christian principles to the world around you. And that sounds pretty darn philosophical to us.
Quest
When you think "quest," you probably think of something like this. But there is, after all, such a thing as a spiritual quest. You might say that Augustine's "Holy Grail" is God himself. Augustine's story actually maps quite nicely onto the Hero's Journey. First, things are well. Then things aren't well. Then Augustine leaves the familiar and enters into the "unknown," when he's in between believing in Manichaeism and believing in Christianity. And there's a mentor who guides our guy Augustine (see our Character Roles section) to his transformation before he returns to his home city (see our Setting section). And you thought that quests had to involve coconuts.