Augustine lived a complex life. As a young man, he explored nearly every religion known, and studied the views of various philosophers. He also committed a wide variety of unethical actions. Yet, despite this complexity, his writings are remarkably clear - he has a talent for helping his reader to understand.
Perhaps what makes Augustine so easy to follow is the passion of his own convictions. He believes that Christianity is absolute truth. He takes Christianity very seriously and expects all others too as well. There was no compromise between paganism and Christianity as he felt one was right and the other wrong. He found Christianity a clear moral guide for life. God gave him everything. And yet, he was not always so saintly. He was a thief. He had a concubine and a child out of wedlock. He admits to thoughts that were not always so clean. Augustine came across as so human. In his book, The Confessions, he revealed his many intimate and sometimes impure thoughts. Romans could relate to what he was saying because they could identify with his experiences. He was not Christian his whole life. For a long while, he followed the ways of the Manichees, a group that borrowed some elements from Zoroastrianism, Buddhism, Judaism, and Christianity. The Manichees believed that there were essentially two worlds, one of light, created by God, and another of evil. The fact that he struggled with inner turmoil about what was the right way, and finding peace when he finds Christianity, was a story that was very persuasive. Phillip Woollcott, a historian, noted, “Augustine had a deep sense of inner unrest to match his times, but in addition, he had the gifts to reify his own inner struggles between good and evil; and in seeking his own creative solution, he gave power and logical cohesion to the youthful church which was largely inspirational at that time.” Romans had turmoil. Would Christianity bring them peace? Augustine certainly felt it could.
Augustine had seen what would finally create peace of mind in a world filled with turmoil. His Roman audience, weary of struggle and meaninglessness, had found all those other religious systems unable to enlighten their minds, and were eager to try Augustine's faith.