The Confessions of St. Augustine ranks as one of the more important books in the history of religion and literature for both its content and its formal innovations.
In terms of form, it is the earliest example of spiritual autobiography in the western traditions, and was in many ways the seminal book in the genre. Many subsequenbt books, such as Rousseau's Confessions or Hogg's Confessions of a Justified Sinner follow an Augustinian pattern.
For historical information, Augustine provides us with unique insights into the daily life and culture of Roman Africa, as well as the social and economic contexts of Christianity and Manicheanism.
Augustine's work was also central to the formation of Roman Catholic theology. His approach to original sin is still accepted as Roman doctrine, as is his notion that the state of graced or lack thereof of the priest does not effect the efficacy of the sacraments (Donatist controversy). He also wrote among the more insightful works on predestination and free will.