4th-5th century: Confessions and City of God by St. Augustine 13th century: Summa Theologica by St. Thomas Aquinas 14th century: The Divine Comedy (includes I

4th-5th century: Confessions and City of God by St. Augustine 13th century: Summa Theologica by St. Thomas Aquinas 14th century: The Divine Comedy (includes Inferno) by Dante Alighieri 20th century: Orthodoxy by G.K. Chesterton, Mere Christianity and The Screwtape Letters by C.S. Lewis, Humanae Vitae (Theology of the Body) by Pope Paul VI