the heresy of denying Catholic Church teaching on original sin, or more specifically the beliefs condemned as heretical in 417 and 418. In her study, Ali Bonner (a lecturer at the University of Cambridge) found that there was no one individual who held all the doctrines of "Pelagianism", nor was there a coherent Pelagian movement, although these findings are disputed. Bonner argued that the two core ideas promoted by Pelagius were "the goodness of human nature and effective free will" although both were advocated by other Christian authors from the 360s. Because Pelagius did not invent these ideas, she recommended attributing them to the ascetic movement rather than using the word "Pelagian". Later Christians used "Pelagianism" as an insult for theologically orthodox Christians who held positions that they disagreed with. Historian Eric Nelson defined genuine Pelagianism as rejection of original sin or denial of original sin's effect on man's ability to avoid sin. Even in recent scholarly literature, the term "Pelagianism" is not clearly or consistently defined. Pelagianism and Augustinianism Pelagius' teachings on human nature, divine grace, and sin were opposed to those of Augustine, who declared Pelagius "the enemy of the grace of God". Augustine distilled what he called Pelagianism into three heretical tenets: "to think that God redeems according to some scale of human merit; to imagine that some human beings are actually capable of a sinless life; to suppose that the descendants of the first human beings to sin are themselves born innocent". In Augustine's writings, Pelagius is a symbol of humanism who excluded God from human salvation. Pelagianism shaped Augustine's ideas in opposition to his own on free will, grace, and original sin, and much of The City of God is devoted to countering Pelagian arguments. Another major difference in the two thinkers was that Pelagius emphasized obedience to God for fear of hell, which Augustine considered servile. In contrast, Augustine argued that Christians should be motivated by the delight and blessings of the Holy Spirit and believed that it was treason "to do the right deed for the wrong reason". According to Augustine, credit for all virtue and good works is due to God alone, and to say otherwise caused arrogance, which is the foundation of sin. According to Peter Brown, "For a sensitive man of the fifth century, Manichaeism, Pelagianism, and the views of Augustine were not as widely separated as we would now