Augustine, the man with upturned eye, with pen in the left hand, and a burning heart in the right (as he is usually represented), is a philosophical and theological genius of the first order, towering like a pyramid above his age, and looking down commandingly upon succeeding centuries. He had a mind uncommonly fertile and deep, bold and soaring; and with it, what is better, a heart full of Christian love and humility. He stands of right by the side of the greatest philosophers of antiquity and of modern times. We meet him alike on the broad highways and the narrow footpaths, on the giddy Alpine heights and in the awful depths of speculation, wherever philosophical thinkers before him or after him have trod. As a theologian he is facile princeps, at least surpassed by no church father, schoolman, or reformer. With royal munificence he scattered ideas in passing, which have set in mighty motion other lands and later times. He combined the creative power of Tertullian with the churchly spirit of Cyprian, the speculative intellect of the Greek church with the practical tact of the Latin. He was a Christian philosopher and a philosophical theologian to the full.

The Christian Church has no shortage of revered figures and saints, but it is difficult to find one that had a more decisive impact on the course of the Church's history than Augustine of Hippo. Augustine was a bishop of Hippo Regius in Africa, but his works, sermons and writings helped hold the Church together even as the Western Roman Empire was in its death throes, to the extent that every major branch of Christianity recognizes him today. The Catholic Church has venerated him as a saint and a Doctor of the Church, Orthodox Christians also consider him a saint, and Protestants and Calvinists cite him as one of the fathers and inspirations of the Protestant Reformation. In many respects, Augustine has provided the theological bedrock for Christians for nearly 1600 years, and as theologian John Leith noted in 1990, "Augustine, the North African of Berber descent, is today the spiritual father of multitudes who are remote indeed from him racially, politically, and culturally." Augustine's voluminous writings also had the effect of making him one of antiquity's most influential philosophers. Though he will always be remembered within the context of Christianity, Augustine studied the works of Virgil, Cicero, and the ancient Greek philosophers, providing a critical bridge between religious and secular philosophy that would in turn inspire St. Thomas Aquinas and similar thinkers. In addition to framing the concept of original sin, it was Augustine who first wrote at length on the theory of just war. Paul Henry, S.J. noted, "In the history of thought and civilization, Saint Augustine appears to me to be the first thinker who brought into prominence and undertook an analysis of the philosophical and psychological concepts of person and personality. These ideas, so vital to contemporary man, shape not only Augustine's own doctrine on God but also his philosophy of man..." On Grace and Free Will, Augustine's doctrine about the liberum arbitrium or free will and its inability to respond to the will of God without divine grace, is interpreted (mistakenely according to Roman Catholics) in terms of Predestination: grace is irresistible, results in conversion, and leads to perseverance.

Jovinianus, about whom little more is known than what is to be found in Jerome's treatise, published a Latin treatise outlining several opinions: That a virgin is no better, as such, than a wife in the sight of God. Abstinence from food is no better than a thankful partaking of food. A person baptized with the Spirit as well as with water cannot sin. All sins are equal. There is but one grade of punishment and one of reward in the future state. In addition to this, he held the birth of Jesus Christ to have been by a "true parturition," and was thus refuting the orthodoxy of the time, according to which, the infant Jesus passed through the walls of the womb as his Resurrection body afterwards did, out of the tomb or through closed doors.