It wouldn't be incorrect to affirm that Augustine is the primary architect of the western Christianity. Even Jesus and Paul were seen by the western Christianity through Augustine's eyes. An examination of Augustine's view of life and its origin will provide the key to many of the perplexing questions regarding the divisions and deviations occurred in the historical development of Christianity. Although Augustine was accepted as the primary father and doctor in the Western church, he was not accepted as a father or a doctor in the Eastern Church. His views were mostly unacceptable to the east.
Augustine developed a view of God different from that of the east, according to which, the Holy Spirit proceeds from both Father and the Son. Later the Nicene Creed was altered by the western Church to include this modification. Moreover, the Holy Spirit was seen as the love that links Father and Son. Such an approach to Trinity was offensive to the East, which had developed its understanding of the Triune God over several centuries. The east had realized that God is incomprehensible, and that God can be known only through His activities. The Trinity made sense only in the presence of the world. However, Augustine's was an objective view of God – an analysis of the ousia (essence) of God without any reference to the world.
Augustine also promoted a low view of humanity, according to which human beings are basically evil, and they are incapable of anything good. The world for Augustine was an evil place, and salvation was escaping from the world and going to the heaven above. Adam's sin was inherited by all humanity, which made all people born with original sin. The Eastern fathers claimed that humanity inherited only the consequences of Adam's sin, and not sin itself.
Greek was the primary language of Christianity as it developed beyond Palestine, and its leaders were Greek-speaking. Christianity was slowly entering the Latin world during the time of Augustine, and Latin was his native language. From his own account, he was a precocious and able student, much enamored of the Latin classics, Virgil in particular. Augustine didn't know Greek, and he couldn't engage in a communication with the Greek fathers. Thus the views and concepts he developed were so different and in some cases even contradictory to the established views in the east. If he had known Greek, the history of Christianity could have been different.
At the age of 19 he developed a passion for philosophy, which was a pursuit of wisdom that included what are now viewed as the separate spheres of philosophy, religion, and psychology. He had a concern with the issue of how to make sense of and live within a world that seemed so adversarial and filled with danger, a world in which so much of what matters most to us is so easily lost [e.g. Confessions IV.x.15]. The one system of thought which was accessible to him and which satisfied his quest was Manichaeism. He remained within this system of thought for nine years. The Manicheans proposed a powerful explanation of the problem of evil: there is a perpetual struggle between co-eternal principles of Light and Darkness (good and evil), and our souls are particles of Light which have become trapped in the Darkness of the physical world. By means of sufficient insight and a sufficiently ascetic life, however, one could eventually, over the course of several lives, come to liberate the Light within from the surrounding Darkness, thus rejoining the larger Light of which the soul is but a fragmented and isolated part.
Later when Augustine was influenced by other thought systems such as Neo-Platonism and Christianity, he repudiated Manichaeism. In his writings against Manichaeism, he focused upon their implicit materialism, their substantive dualism whereby Darkness, and hence, evil, is granted a co-eternal, substantial existence opposed to the Light, and their identification of the human soul as a fragmented particle of the Light. Although Augustine is vehement in his repudiation of the Manicheans, one can see the influence of the Manichean world-view in Augustine’s thought.