Grace and Punishment

The Augustinian concept of Grace is based on the thesis that all 'good' is derived from the Abrahamic deity.  However, that thesis does not entail that only good is derived from the deity.  Furthermore, the espousal of the proposition that only good is derived from that deity faces the challenge of explaining God's 'greatly multiplying the birthing pains of the Eve and her descendants', to paraphrase Genesis 3:16.  Now, it might be argued that God's action in this passage is a just punishment for an evil deed, and, hence, that the infliction of misery is a 'good'.  However, there is no corresponding divine 'justice' for good deeds, i. e. no divine rewarding.  For, a 'reward' is a response to an independently 'good' action, the possibility of which is excluded by the concept of Grace.  Hence, while Augustine might intend Grace to express the thesis that all good is derived from God, his concept, when fully developed, also portrays his deity as an unjust source of misery, and, so, as an object of fear.