Now if this is a true account of what constitutes the right and the wrong use of personification, have we not grounds for holding Celsus up to ridicule for thus ascribing to Christians words which they never uttered? For if those whom he represents as speaking are the unlearned, how is it possible that such persons could distinguish between “sense” and “reason,” between “objects of sense” and “objects of the reason?” To argue in this way, they would require to have studied under the Stoics, who deny all intellectual existences, and maintain that all that we apprehend is apprehended through the senses, and that all knowledge comes through the senses.
But if, on the other hand, he puts these words into the mouth of philosophers who search carefully into the meaning of Christian doctrines, the statements in question do not agree with their character and principles. For no one who has learned that God is invisible, and that certain of His works are invisible, that is to say, apprehended by the reason, can say, as if to justify his faith in a resurrection, “How can they know God, except by the perception of the senses?” or, “How otherwise than through the senses can they gain any knowledge?”
For it is not in any secret writings, perused only by a few wise men, but in such as are most widely diffused and most commonly known among the people, that these words are written: “The invisible things of God from the creation of the world are clearly seen, being understood by the things that are made.” From whence it is to be inferred, that though men who live upon the earth have to begin with the use of the senses upon sensible objects, in order to go on from them to a knowledge of the nature of things intellectual, yet their knowledge must not stop short with the objects of sense.
And thus, while Christians would not say that it is impossible to have a knowledge of intellectual objects without the senses, but rather that the senses supply the first means of obtaining knowledge, they might well ask the question, “Who can gain any knowledge without the senses?” without deserving the abuse of Celsus, when he adds, “This is not the language of a man; it comes not from the soul, but from the flesh.”
Source: Against Celsus (New Advent)