Pre-Enlightenment thinking had largely emphasized the nature of what-is-real in itself antecedent to the mind's knowledge of it. This branch of philosophy is called ontology. This type of philosophical inquiry had begun with the earliest Greek philosophers and resulted in the development of ontological categories classically formulated by Plato and Aristotle. Even the creeds of the church and the development of Christian theology adapted these Greek categories for expressing the message of the Bible.
The Early Christian Apologists. The earliest Christian intellectuals in the second century a.d. where called apologists (apologia, “a defense”) because they felt the need to defend the Bible. These men had been converted from paganism, had already been trained in philosophy, and had read widely in the worldly wisdom of their day. Their intent was to show that the biblical faith was based on thoughtful consideration of the facts and that its truth could be readily embraced by any educated citizen of the Roman Empire.
Their success in showing that the Bible is intellectually respectable enhanced the missionary expansion of the church, for historians have shown that the greatest threat to the spread of the Christian gospel in its earliest days was not the mystery religions with the barbaric idea of the dying and rising of gods. Though the masses of people were not well educated and were easily swayed by mythological folklore, the faith of the earliest Christians simply did not fit into this irrational network of beliefs. The appeal of these believers to historical facts as a basis for their faith put their beliefs altogether outside the framework of myth. That was not the case with popular religions that were embraced by their pagan neighbors throughout the Roman Empire.
The Threat of Stoicism to Christian Faith. The real threat to the Christian missionary expansion came from the Stoics.Paul Tillich, The Courage To Be (New Haven: Yale Univ. Press, 1952), 9-10. These intellectuals developed a philosophy of religious consolation in a world troubled with political upheaval, personal tragedy, and family disintegration. Borrowing elements from the thinking of Plato and Aristotle, they espoused a rational view of the universe that offered the worshiper a pantheistic union with God and a fellowship of universal brotherhood. The pursuit of God and the pursuit of Truth were one and the same goal. Salvation was for the few, not the masses, since the intellectual cultivation of one's mind was the only adequate preparation for enjoying oneness with God.
Stoicism specifically rejected the traditional folklore of popular religion. Stoicism's appeal lay in the ability of its ideas to explain the meaning of life and its therapeutic effect to calm one's panic-stricken feelings of dread.
Stoicism's religious philosophy was in direct conflict with the claims of the newly emerging Christian faith. Unlike the abstract and impersonal God of Stoicism, Christian believers claimed that God was personal, infinite in goodness, wisdom, and power, and was the Creator and Sustainer of the universe. They further claimed that access to this personal God was mediated through his incarnation in one Jesus of Nazareth, without whom it was impossible to have personal and intimate fellowship with God.
Salvation was also dependent, not only upon the historical appearance of God in Jesus Christ, but upon his personally chosen witnesses. Unlike Stoicism, which limited salvation to the intellectual elite, Christian faith offered universal salvation to all peoples of the world of whatever rank or education. Good news, not simply good views, was the decisive difference between Stoicism and Christianity. Both claimed that salvation was the result of knowing the Truth, but the gospel of Jesus Christ is the Truth. Truth is not merely a beautiful system of ideas that one intellectually embraces, but Truth is the announcement of a personal God whose Son has brought light and life to all who will embrace his personhood. God's truth was historically and factually made known in his created world, unlike the popular, mythical religions whose stories were in no way interested in dependence upon facts and documented events of history. Thanks in large part to writings of early Christian apologists and our early church Fathers, along with the martyrs who laid down their lives for the sake of the truth of the gospel, the missionary expansion related in the book of Acts continued until the Roman Empire and the entire Western world had largely embraced Christianity, even if some of it was an aberration. For Christian faith had proved itself intellectually superior to the religious philosophy of Stoicism, and it was felt to be emotionally more satisfying than the ecstatic popular religions of the ancient world.
Christianizing Greek/Roman Thought. The conversion of the Roman Empire and the Western world was, of course, not an easy process. Many skirmishes with paganism continued, and some unfortunate elements of the popular religions made their way into the Christianized world. Also, some negative elements of pagan philosophy were appropriated by the church. On the other hand, many positive elements of philosophical traditions that the church adapted from the classical world helped to make explicit the essence of the gospel.
The development of Christian doctrine was generally successful in synthesizing the message of the gospel with the philosophy of Plato and Aristotle. In fact, the early Christian thinkers were able to use the categories of Plato and Aristotle (and Stoicism) to say things that Greek and Roman philosophers were unable to say because they lacked the biblical revelation. Based on the concept of general revelation, Christian faith acknowledges that a measure of God's truth is accessible to all people. For example, Greek thinkers developed a system of logic and philosophy that made it possible to construct a rational view of the world, and these categories were foundational for the church in developing our system of beliefs. In this way, the church used Greek categories to say things that Greeks themselves were unable to say.
For example, Plato developed a view of the supersensible level of reality—that there is a realm of reality that transcends the five senses. This intangible world is not subject to the decay and flux of the temporal world. Augustine borrowed this platonic category to explain the meaning of spiritual realities. To be sure, Plato did not understand the Christian meaning of the supernatural world—that God created the world out of nothing and that he is totally different in his essence from the natural world. In adapting Plato's concept of the supersensible world, Augustine was able to explain the Christian doctrine of God and creation, which was totally unknown to Plato himself.