Manichaeism was dualistic system of thought which had a significant following at the time. It derived from the teachings of Mani, a Persian philosopher. Manichaeism was a form of Gnosticism in that it proposed the existence of two worlds at war with one another: the world of light, love, mind and spirit; and the world of darkness, evil, hate and the flesh. For Augustine this dualist corruption of Christianity provided the suitable answer to the problem of evil which he could not see in Christianity. These two worlds were constantly in conflict, and Augustine recognized the conflict in himself. While Manichaeism conceded that some people, the Perfect, could overcome the conflict and devote themselves to the higher things of life; for the majority of believers (the Hearers), it would be a continuous struggle. Although his objection to Christian theology was doubtless deep, Augustine could have been accused of a certain degree of intellectual snobbery at this stage of his life. He was repulsed by the lack of sophistication he found in his Christian catechetical content and in the biblical writings, which he found rhetorically disappointing. This crudeness contrasted sharply with higher plane of enlightenment promised by Manichaean teaching, enlightenment Augustine found extremely attractive.

After the completion of his studies at Carthage, Augustine returned to Thagaste to teach rhetoric and Manichaeism, even converting his patron, Romanianus. Knowledge of his involvement caused his mother to eject him from home for a while. During this time at Thagaste, Augustine faced the reality of death. He found himself at the bedside of a friend who was dying. A priest who was also there proceeded to baptize the dying young man (much to Augustine’s disdain) and he made a miraculous recovery. While both Augustine and the friend had previously been skeptical, the friend’s new-found piety following his recovery affected Augustine and he was further shaken when the friend died two weeks later. The event (recounted in the Confessions, IV. iv), marked the beginning of a change of heart and mind in Augustine.

Although he found Manichaean teaching a more satisfying explanation for the problem of evil that Christian theology, Augustine still had unanswered questions. Those around him assured him that a meeting with Faustus of Mileve, the Manichaean bishop believed to be an enlightened member of the Perfect, would satisfy his objections. Augustine's eventual rejection of Manichaean philosophy came as a result of meeting and talking with Faustus. Much to his chagrin, Augustine found him to be simple-minded and barely literate. Clearly, Manichaeism did not hold the answers Augustine desperately sought.