If, with the object of convicting the rivals and persecutors of Christian truth, from their own authorities, of the crime of at once being untrue to themselves and doing injustice to us, one is bent on gathering testimonies in its favour from the writings of the philosophers, or the poets, or other masters of this world's learning and wisdom, he has need of a most inquisitive spirit, and a still greater memory to carry out the research. Indeed, some of our people, who still continued their inquisitive labours in ancient literature, and still occupied memory with it, have published works we have in our hands of this very sort; works in which they relate and attest the nature and origin of their traditions, and the grounds on which opinions rest, and from which it may be seen at once that we have embraced nothing new or monstrous— nothing for which we cannot claim the support of ordinary and well-known writings, whether in ejecting error from our creed, or admitting truth into it.
But the unbelieving hardness of the human heart leads them to slight even their own teachers, otherwise approved and in high renown, whenever they touch upon arguments which are used in defence of Christianity. Then the poets are fools, when they describe the gods with human passions and stories; then the philosophers are without reason, when they knock at the gates of truth. He will thus far be reckoned a wise and sagacious man who has gone the length of uttering sentiments that are almost Christian; while if, in a mere affectation of judgment and wisdom, he sets himself to reject their ceremonies, or to convicting the world of its sin, he is sure to be branded as a Christian.
We will have nothing, then, to do with the literature and the teaching, perverted in its best results, which is believed in its errors rather than its truth. We shall lay no stress on it, if some of their authors have declared that there is one God, and one God only. Nay, let it be granted that there is nothing in heathen writers which a Christian approves, that it may be put out of his power to utter a single word of reproach. For all are not familiar with their teachings; and those who are, have no assurance in regard to their truth.
Far less do men assent to our writings, to which no one comes for guidance unless he is already a Christian. I call in a new testimony, yea, one which is better known than all literature, more discussed than all doctrine, more public than all publications, greater than the whole man— I mean all which is man's. Stand forth, O soul, whether you are a divine and eternal substance, as most philosophers believe if it be so, you will be the less likely to lie,— or whether you are the very opposite of divine, because indeed a mortal thing, as Epicurus alone thinks— in that case there will be the less temptation for you to speak falsely in this case: whether you are received from heaven, or sprung from earth; whether you are formed of numbers, or of atoms; whether your existence begins with that of the body, or you are put into it at a later stage; from whatever source, and in whatever way, you make man a rational being, in the highest degree capable of thought and knowledge—stand forth and give your witness.
But I call you not as when, fashioned in schools, trained in libraries, fed in Attic academies and porticoes, you belch wisdom. I address you simple, rude, uncultured and untaught, such as they have you who have you only; that very thing of the road, the street, the work-shop, wholly. I want your inexperience, since in your small experience no one feels any confidence. I demand of you the things you bring with you into man, which you know either from yourself, or from your author, whoever he may be.
You are not, as I well know, Christian; for a man becomes a Christian, he is not born one. Yet Christians earnestly press you for a testimony; they press you, though an alien, to bear witness against your friends, that they may be put to shame before you, for hating and mocking us on account of things which convict you as an accessory.
Source: The Soul's Testimony (New Advent)