The central theme in all the writing of Augustine is the sovereign God of grace and the sovereign grace of God. Indeed, Saint Augustine is called the Professor of Grace (Doctor Gratiae in Latin). This was because of his great work against the Pelagians who practically denied the need of grace for reaching eternal life. In this, Augustine showed very well the total dependence of human beings on God.
Augustine is forced to conclude that the only way for a human being to escape sin is through the grace (gratia in Latin) of God. In his Confessions, after having already found that he cannot escape sin on his own, he turns to the Scriptures, this time taking his text from the Epistle to the of Romans. In Romans, he reads, "Who than should deliver me from the body of this death, but Your grace only, through Jesus Christ Our Lord?"
Augustine realises the truth in this statement and says to God that "all my hope is nothing except in Your great mercy." God answers and Augustine rejoices, telling God that "it is only by Your grace and mercy that You have melted away the ice of my evil." He asks God to show him the path he should take. Though his temptations do not vanish with his conversion, Augustine now has the capability to deal with them. "You commanded me ... and since you gave me the power, it was so done."
Grace, for Augustine, is the freedom of God to act without any external necessity whatsoever - to act in love beyond human understanding or control. It is the freedom of God to act in creation, judgment, and redemption; to give his Son freely as Mediator; to endue the Church with the power and guidance of the Holy Spirit; to shape the destinies of all creation and the ends of the two human societies, the "city of earth" and the "city of God."
As seen by Augustine, grace is the love and favour of God towards human beings. It is a favour that we have not merited, yet is made available to us. It touches the inmost heart and will of a person. It guides the lives of those called to be faithful. It draws and raises the soul to sorrow for offending God, to faith, and to the praise of God. Augustine never wearied of celebrating the abundant mercy and grace of God.
Grace transforms the human will so that it is capable of doing good. It relieves a person's religious anxiety by forgiveness and the gift of hope. It abolishes the ground of human pride. The grace of God became visible in Jesus Christ, and it now remains in the Holy Spirit in the Church.