Augustine's The Confessions Of St.

Christianity is what it is today because of the philosophical ideas of Plato and Aristotle. The ideas that they have presented a way of thinking that was different from what most of the world was accustomed to and therefore it shed light upon the viewpoint of many people. While their beliefs were not directly tied into religion, but they had followers who did so with their own views; Augustine shared views with Plato and Aquinas shared views with Aristotle.
Plato was the first philosopher out of the ones mentioned beforehand, and therefore it is safe to assume that all of their ideas tie in with his as he was the one who mentored Aristotle. Plato was a believer in the idea of metaphysical dualism, and as such his main philosophy can be summed
up with the claim that while the physical world and the intelligible world exist at the same time, the physical world is only a shadow of the intelligible world. This is to say that what is seen comes from how the observer perceives it, and since everyone perceives things differently there is no definite physical form, and only a perfect ideal form. This is later looked at by Augustine in terms of God, but since God is not material, he has no flawed forms instead only the shadows of his presence can be observed.

Aristotle, was a disciple of Plato, and thus carries some of his basic ideas. One of these is the idea that the main component separating humans from animals is the human being’s ability to reason. (Atkinson) Besides this many of Aristotle’s prominent views were very different from Plato’s, mainly in the sense that he was more realistic in terms of the physical world. Aristotle believed in that what can be perceived and left behind his Platonism beliefs for the ideology of empiricism. (Barnes) This means that he conformed to the idea that all knowledge is derived from sense-experience. So everything that humans know and do are in according to what has been experienced. Taken into further account Aristotle breaks this idea of why humans do what they do down into four specific causes: the material cause, formal cause, efficient cause, and the final cause. The final cause is the most important to remember when trying to tie Aristotle’s beliefs in with Aquinas’ later.
As previously stated, Plato and Aristotle did not influence Christianity directly, instead it was through some of their followers; Augustine was one such follower of Plato.
Platonism was the ideology the Plato had and a branch of this was known as Neoplatonism, which was what Augustine had taken to. (TeSelle) Neoplatonism was not as concrete in having one main idea, so it is important to pinpoint what Augustine’s take on it was. In an autobiographical work, The Confessions of St. Augustine, he writes on how Logos is the divine eternal world. In this writing he talks about the idea that the things being perceived are only a shadow of the intelligible world, “But having then read those books of the Platonists, and thence been taught to search for incorporeal truth, I saw Thy invisible things, understood by those things which are made.”(Confessions 68) In the search for the truth, he claims to find God in this method, as God is not material and therefore cannot be seen besides through the “shadow” he casts upon this world. Augustine has pointed out that God is not composed of matter, with this in mind, he must still be composed of something. This something that Augustine defined him as is “Good” and he notes that, “Those who accept this can live the good life even under earthly conditions, provided they look for blessedness to God alone, the supreme Good.”(Burleigh, 223) This idea was adopted by Christianity as a whole and can also be seen in the Bible when Jesus says, “Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind.” (Matthew 22:37) Essentially loving God, is loving goodness, and this is the ideology of the Christian
way. Aquinas was another philosopher that took preexisting ideas and brought them to religion. His ideas came from Aristotle, mainly Aristotle’s analysis of physical objects and sense of perception and intellectual knowledge. (McInerny) He was a leading component when it came to trying to prove God’s existence through human reason or observations of the natural world. More importantly he said that everything that humans do is for a purpose, ultimately happiness. (Pursuit of Happiness) He ties this in with Christianity as good is happiness, and therefore everything done by humans should be for him so that they may be in an eternal fellowship with him. If life is lived in such a way, then in death, God grants humans the gift of unending happiness by seeing his essence. It is to be noted that since God can be viewed as the source of all good, acts of evil will not bring one closer to God, even if it creates happiness.
Without these philosophies the perception of the Christian religion and what it means to be Christian would have been entirely different. It is likely that the base idea of God would still be present, but as to determining what God is, that would still be widely debated by Christians. Even more so, without knowing what God is it would be hard to know what God wants, leaving the question of what “What should I do as a Christian?” Thanks to Aristotle and Plato, Augustine and Aquinas were able to answer these questions and gave way to the common belief that Christians share on such topics.