The Impact of Christianity on Philosophy and Thought

Contributions of Christianity to Philosophy:
While philosophy explains what things are, religion speaks of man’s destiny. Many pages contain biblical philosophical theses that have clearly changed the course of human thought. The task of the first philosophers was to translate the content of Christian revelation into rational categories, making faith reasonable. Their main issues included the establishment of God’s relationship with the world, the relationship between faith and reason, the mystery of evil, the nature of the soul, human destiny after death, and the surrender of interest in Christ. The first Christian philosophers were more theological than philosophical. They explained and defended that Christianity is not merely a philosophy, but it needs philosophy for two reasons: to define dogma against internal heresies and to defend against an incomprehension that leads to persecution.
Among the contributions of Christianity to Greek philosophy is the very argument about the existence of God. St. Paul argued that human reason, apart from the spectacle that the world provides, can know the existence of God and His eternal power. This implicit philosophical rationality of the Christian religion facilitated the worship of many Greeks. The notion of creation is a significant departure from Greek thought. Christianity marks a profound division in the history of religion, bringing an entirely new idea of the existence of the world and man. The difference starts from the first line of Genesis, as the notion of creation is completely irrelevant to Greco-Roman thought. The Greeks considered the cosmos to come from eternal matter, arranged either randomly or by the intelligence of a demiurge, or a first mover, or a pantheistic logos. In any case, it is an everlasting cosmos that simply exists, and whose existence is perceived as an obvious and necessary fact: any questions about its origin would be a question without sense. Monotheistic Greek thought had never raised the problem of whether God was one or many. In the Bible, God’s transcendence is absolute, without any further opportunity to deify anything. To know God is to understand who He is, and this is the answer: ‘I am’ is a philosophical answer that seems to define existence. God is the only being in whom essence and existence are identical. There is but one God, the Self, which is the cornerstone of any Christian thought.
Providence in Philosophy:
If Aristotle seems to ignore this notion, Socrates, Plato, and the Stoics intuited it. Providence coincides with fate, and it is only the rational part of the need to produce things. In contrast, the Bible presents the providence of a personal God over every human being.
Legislation:
The Greeks had identified the law of morality with the law of nature: a law prevailing at the same time for gods and men. The notion of a lawmaker is largely absent from Greek philosophy. On the contrary, God instructs man through biblical laws on what to do. Thus, virtue and holiness consist in such obedience.
Immortality and Resurrection:
The notion of the soul is a Greek creation, introduced by Socrates and Plato, and studied in depth by Aristotle. Without a doubt, the psyche symbolizes one of the best concepts of Greek metaphysics, and Western man is rarely able to think of himself without referring to the soul and body. While the Platonic-Pythagorean tradition believes the soul is of an immortal nature, the Christian tradition presents something much bolder: the resurrection of the dead, which involves the soul and the body returning to life. This is one of the hallmarks of the new faith and a serious obstacle to its acceptance by Greek philosophers.
Revolution of Values:
If the Greeks and Romans aspired above all to happiness, Christians have as their goal to love God above all things and their neighbor as themselves. To dispel any shadow of doubt, Jesus commanded to love your enemies and pray for your persecutors and slanderers. This message represents the most radical revolution of values in human history.

Differences with Greek Philosophy:
The Problem of Knowledge:
Regarding the possibility of attaining truth, Greek philosophy held three positions: skepticism, relativism, and realism. Christianity emerged amid a plurality of philosophical schools that made skepticism the dominant mentality. In contrast to this view, Christianity asserts the existence of truth and affirms the possibility of attaining it through a superior source of knowledge to human reason: divine revelation.
The Problem of Reality:
Christianity conceives an integrated reality of God and the world. The world and all beings within it have been created from nothing. This notion of creation is inconceivable for Greek monotheism and collides with Greek and Roman polytheism.
The Problem of Humanity:
Christian anthropology affirms three key issues: creation in the image and likeness of God, the immortality of the soul, and the resurrection of the bodies. For some Greek philosophers, the soul was mortal (Aristotle) or material and corruptible (Democritus, Epicurus). Others, like Plato and Pythagoras, argued for immortality, but the concepts of divine sonship or resurrection of the bodies were unknown.
The Ethical Problem:
The ethics of Greek schools had a strong intellectual character: human evil is rooted in ignorance. Christianity places the emphasis on free will and the need for divine help (grace) to act well. This concept was unexpected for the Greeks. On the other hand, Christian ethics is presented as a figure that prioritizes human happiness over individual goals and the tranquility of mood (Stoics), reasonable pleasure (Epicurean), the harmony of the soul (Plato), or virtue (Aristotle), without any reference to selfless love for others.
The Political Problem:
The distinction between political and religious dimensions is a complete novelty for Greek philosophy and state. Religion had gone hand in hand from the origin of Mesopotamia. In Greek cities, the state had its own religion, which citizens were expected to practice. The cost of dissenting in religious life was high. Socrates was condemned, and the emperor was deified and worshipped. Christians were the first to deny the divinity of rulers and to separate the spheres of religion and politics.
The Problem of the Sense of History:
For Christianity, history is the drama of humanity’s surrender, culminating in a final reward and punishment. God Himself has entered history by becoming man. This problem exists in Stoic philosophy, which finds a philosophy of history that plays the key role of human becoming in a circular manner, where cycles happen in endless repetition.

Contact Points:
The vast differences between Christianity and Greek philosophy are insurmountable in the case of sophists, skeptics, or relativists. There is also no possibility of understanding with the materialism of Democritus and Epicurus, which denies the existence of spiritual realities. This explains why some Church Fathers rejected Greek philosophy and opposed any dialogue with it. Others, however, engaged in dialogue based on certain precious contacts. It was through a convert like St. Augustine, who was well acquainted with Greek philosophy, that some similarities between Christianity and Christian thought developed in Platonism. Thus, the Platonic character adapted Plato’s thought to the main tenets of Christian contact. The points of contact were found in Plato’s four virtues:

  • The existence of the world of ideas, a different spiritual world—a demiurge that, while not creative, offers some resemblance to the Christian idea of God.
  • A unique and superior being to all others, similar to monotheism.
  • Immortality of the soul and its rational tests. Christianity rejected the Platonic concepts of pre-existence and reincarnation of souls but agrees with the Greek philosopher that the true destiny of the soul is not in this imperfect world.

Some ideas of the Stoics were also exploited by Christians. Thus, the first philosophers recognized the existence of a reason that intelligently leads to the same human destinations. Christianity coincides with the Stoics and some Cynics in the importance of leading a modern and austere life. In the 8th century, St. Thomas Aquinas found important contact points with Aristotle: an ethics of virtue and a mover that serves to explain certain aspects of the Christian God.

Truth and Enlightenment:
St. Augustine always thought that skepticism is impossible, as it contradicts truth itself: it is true that doubt exists. In a celebrated formula, Descartes said, ‘I think, therefore I am.’ St. Augustine says, much like, ‘If you doubt, you exist.’ St. Augustine interprets the problem of knowledge as a multipart process:

  1. Through sensations, the soul knows the objects of the outside world.
  2. However, the soul is able to judge the contingent world known by the senses and universal criteria, whether mathematical, geometric, or moral.
  3. Then arises the question of how these criteria reach the soul for knowledge. Does the will make the soul? It seems not, since the will is also changeable, while the criteria are immutable.

Remembering Protagoras, St. Augustine would say that in him, truth is far from all things, and the intellect itself is measured by it.
The immutable criteria of truth are the intelligible forms that Plato spoke of. St. Augustine called the Platonic theory of ideas ‘rationes ideasy,’ conceding that its value is such that no one can be a philosopher without being aware of these ideas. He states that ideas are the fundamental forms or stable and immutable things. Although they do not come into being or perish, everything that is born and dies is created and formed based on these models. However, Augustine corrects Plato in two points:

  1. He turns ideas into thoughts of God.
  2. He restates the doctrine of reminiscence and speaks of enlightenment.

The Platonic recollection involved the pre-existence of the soul, a possibility that is excluded by Augustinian creationism. St. Augustine describes enlightenment in this way: just as in light, one may notice three things: that there is light, that it shines, and that it illuminates. In the ineffable God, whom we want to know, there are, in a sense, three principles: existence, intelligibility, and the ability to make all other things understandable. In the light of God, man discovers the eternal truths imprinted in his heart: theoretical and practical truths that should govern free conduct, which are not arbitrary but designed by God for human nature, because He created man to be what He wanted him to be. The will is free, but the perfection of that freedom is marked by the moral law, and love for God is a must. St. Augustine believes that the notion of truth supports multiple meanings, the highest of which is identified with God. Therefore, as we shall see, the proof of the existence of certainty and truth in human understanding coincides with the demonstration of the existence of God.

Reason and Faith:
Based on a text by the prophet Isaiah, St. Augustine never tires of repeating that faith illumines reason and that reason leads to the summit of faith. In a celebrated formula, he tells us that we understand in order to believe, and we believe in order to understand.
The Augustinian position is far from fideism, which always represents a form of irrationalism. Faith does not supplant intelligence; rather, it stimulates and illuminates it. The settlement is a rational faith, for without thinking, there could be no faith. Part of the reward of faith is increased clarity. Similarly, faith is the reward of good reason, and reason in no way eliminates faith, but strengthens and clarifies it: man must seek God with all his intelligence. Therefore, faith and reason are complementary. Tertullian’s credo is completely foreign to St. Augustine. If reason removes a rational faith and believes only what can be seen and touched, and if faith takes away reason, one may become a fideist and do irrational things in the name of faith.
Augustine invokes the Platonic, and here it is worth remembering that he recommended reaching ultimate truths through one’s own intelligence and the authority of wise men, unless one can make that journey in a more secure and lower-risk manner, more solid on a ship, that is, trusting in divine revelation. For Augustine, this ship is Christ crucified. Thus, we say that no one can cross the sea of life if not driven by the cross of Christ. This is precisely the philosophy of faith, a message that has changed Western thought for many centuries. It is reason that accepts the object of faith: Christ. It is reason that examines the motives of credibility. The Church commands us to believe but offers assurances that reason can evaluate. It commands us to open our eyes to historically verifiable truths. For Augustine, believing means understanding, while we insist that the best understanding of faith is given by faith itself. Faith illuminates man and grants him as a reward the highest intelligence. The process of drawing together the Augustinian faith and reason is the understanding of belief, to understand and believe, and to understand love. His supreme desire is to love the truth, and he does not mind whether the procedures to achieve this belong to faith or reason. For Augustine, the full truth is found only in Christianity, with which we must contrast the doctrines of philosophers. Thus, his firm belief not only prevents him from being open to philosophy but also leads him to engage with it in a manner that is both found and profitable. For the young Augustine, dialectic philosophy was conceived as the pinnacle of wisdom. After his conversion, Augustine admits that his admiration for interior philosophy was overstated, because happiness lies in loving God and living with Him in the afterlife, and the path to this is not philosophy but Christ.

The Existence of God:
The contents of the Augustinian philosophy can be summarized in a line from his soliloquies: ‘I know and love God.’ Nothing else? Nothing at all. Not even in his momentary crisis of skepticism did St. Augustine come to doubt the existence and providence of God. His convictions are rooted in his soul since his earliest education and contributed decisively to his regaining of faith. The negation of the existence of God seems a little crazy because His existence is so obvious that it suffices to affirm a simple reflection. In particular, the existence of God can be demonstrated through three paths:

  1. The existence of truth.
  2. The existence of a contingent and ordered world.
  3. The universal consensus.

The Existence of Truth:
Man is capable of eternal and immutable truths, independent of sensations. Such is the case, for example, with mathematical truths. They are also universal and unchanging ideas of good, beauty, and justice. If so, these models must have their foundation unchanged in being eternal and perfect, because they cannot be derived from the mutable and temporal. Transcendence:
Upon discovering the truth, thought has found the existence of God, in that what it has discovered as superior to man possesses the attributes of God: eternity, immutability, and necessity. The three steps of reasoning would be:

  1. There is an eternal and immutable truth present in thought.
  2. Thinking is not sufficient reason for this truth.
  3. Therefore, there is God, its reason, and sufficient contingency.

The Order of the World:
The Augustinian demonstration of God from His works is classic in the history of philosophy. St. Augustine reminds us of Psalm 73: ‘On the operations of the body, I know you live; what you cannot know, by the works of creation, to know the creator?’ We read in the City of God: even putting aside the testimony of the prophets, the world itself, with its tidy variety and mutability, tacitly proclaims that it has been made, and made by a great, ineffable, and invisible God. The Universal Consensus:
Evidence traditionally known by the name of consensus gentium, found in ancient pagan thinkers, is summarized by Augustine in three cases. The purpose of the show is not merely intellectual, as it could be in Aristotle. St. Augustine is interested in knowing God to love Him and recognizes Him in confession.

The Problem of Evil:
If God is good and from Him all things stem, why is there evil? This problem haunts St. Augustine and made him take a first step toward a Manichean solution. However, he later reflected that evil is always a corruption of good, and that it does not require a positive start but arises from the degeneration of something previously good. Evil is not a being, nor a substance, but the deprivation of something that corresponds to being. It is a being that results from a deficiency in a world that was created defective by God. Physical evil has a very precise meaning for those who philosophize in faith: original sin is a consequence of moral evil. Evil dwells, on the contrary, comes from human freedom given by God. God wanted to inscribe in the human heart the moral law, which commands to avoid evil, yet respects our freedom not to follow that law, because without the power of choice, man could not live rightly, as he can only act if he does so voluntarily. St. Augustine invests moral intellectualism of the Greeks and emphasizes the role of free will. He affirms that if man had no freedom, how could he be justly condemned for sin and rewarded for good deeds? For there would be no sin or good deed if it were not dependent on freedom. However, if freedom has been granted for good, how is it that man abuses it and does wrong? This, like pain and death, is the result of original sin.


Man: Body and Soul
Everything human, from the slightest feeling, comes from a being whose life is both organic and spiritual, sensus et mentis. Therefore, soul and body are not two opposing principles, as in Plato and Descartes, but constitute the unity that is man. The body and soul are not separate; the soul is the vital energy of the body, sensitive and intellectual. Man is not only body and soul, but a being composed of both. The soul is the whole man, but the body is not the whole man; rather, it is the bottom. When soul and body are united, they are called man, a name not lost when we talk about them separately. More briefly, animal rationale: man is mortal. St. Augustine no longer sees the body, as Plato and the Pythagoreans did, as an appendix or a burden: it belongs to human nature and thus falls within the definition of man. Augustine dedicates much time to thinking about the origin of the soul. He rejects the Platonic pre-existence and affirms that the soul of the first man was directly created by God. However, difficulties arose with the descendants of Adam. He rejects the emanation of the Neoplatonists, Gnostic and Manichaean ideas, and the materialistic traducianism of metempsychosis, but is amazed at the acceptance of creationism, as it was incompatible with the doctrine of inherited original sin. In the end, he seems to lean toward a via media of creationism or generation traducianism: no doubt that God creates each soul, but he doubts whether it is created from the soul of the parents, by way of generation, or from nothing. St. Augustine rejects the Platonic idea of three souls: in man, there is only one soul, which enters and verifies the entire body, and it is all in all and each of the parts of the body. The soul is also enclosed in the body as a result of punishment, but this coupling is natural. The intellectual soul is spiritual, and thus is able to live and know that it lives, to know and understand. The human soul is also, in St. Augustine’s view, immortal. For this knowledge and immortality, man is the image of God and can find God, as in a mirror, in the privacy of his soul. Therefore, apart from God, man is empty of his own entrails. The weight that moves the soul is love, and that love, understood as charity, is the center of all Augustinian ethics, summarized in the famous imperative: love and do what you want.

Philosophy of History:
Christianity teaches that, having God as mankind’s creator, the first man disobeyed God, and all his descendants have since struggled between love of God and love of self. St. Augustine describes a struggle between love and pride, between sin and redemption, between liberty and divine grace. This struggle transcends the natural order and constitutes the inner drama of each person, as what is at stake is salvation or eternal condemnation. Just as there are men who love God above themselves, and men who love themselves more than God, there are also two cities founded by each of the two loves: the earthly city and the heavenly city. The conviction and eternal happiness await the citizens of both, but throughout human history, the civitas dei and civitas terrena have always fought. Some pagans attributed the vicissitudes of the Roman Empire to the abandonment of God and Christianity. Christian apologists had already addressed these accusations. St. Augustine, a privileged spectator of the fall of Rome, wrote the City of God as a great apologetic work in which he reflects on the meaning of history. Creation implies an ontological link between creator and creature: the world might never have happened, but once it exists, there is a creator. The creator has shown us that history will conclude with the final trial, which will undertake the separation of the two cities that have coexisted for centuries. This trial signifies the final victory of good over evil, light over darkness, and the kingdom of God over that of Satan. There is a personal story starring every man, as is evident from the Confessions, and a history of humanity, but both the beginning and the end of both stories are in the hands of God. The state, a deeply natural institution, must ensure welfare, peace, and justice, steeped in Christian values as much as possible, since all authority comes from God. At the same time, it must support the Church in its mission, for no state is better established and preserved than one based on faith and strong harmony, when the highest good and true God is loved by all, and men flow toward each other.