Religious fervor and psychological insight characterize the spiritual autobiography of the distinguished fifth-century churchman. Writing some years after his conversion to the Catholic faith, Augustine praises God's grace during his years of spiritual wonderings, laments his sins, and describes his youth in North Africa. Augustine, a Latin church father, is one of the most important figures in the development of Western Christianity. Augustine established the concepts of original sin and just war. Many Protestants, especially Calvinists, consider him to be one of the theological fathers of Reformation teaching on salvation and divine grace.