Now, in order to grant that there did exist a healing spirit named Æsculapius, who used to cure the bodies of men, I would say to those who are astonished at such an occurrence, or at the prophetic knowledge of Apollo, that since the cure of bodies is a thing indifferent, and a matter within the reach not merely of the good, but also of the bad; and as the foreknowledge of the future is also a thing indifferent— for the possessor of foreknowledge does not necessarily manifest the possession of virtue— you must show that they who practise healing or who forefell the future are in no respect wicked, but exhibit a perfect pattern of virtue, and are not far from being regarded as gods.
But they will not be able to show that they are virtuous who practise the art of healing, or who are gifted with foreknowledge, seeing many who are not fit to live are related to have been healed; and these, too, persons whom, as leading improper lives, no wise physician would wish to heal. And in the responses of the Pythian oracle also you may find some injunctions which are not in accordance with reason, two of which we will adduce on the present occasion; viz., when it gave commandment that Cleomedes — the boxer, I suppose— should be honoured with divine honours, seeing some great importance or other attaching to his pugilistic skill, but did not confer either upon Pythagoras or upon Socrates the honours which it awarded to pugilism; and also when it called Archilochus “the servant of the Muses”— a man who employed his poetic powers upon topics of the most wicked and licentious nature, and whose public character was dissolute and impure— and entitled him “pious,” in respect of his being the servant of the Muses, who are deemed to be goddesses!
Now I am inclined to think that no one would assert that he was a “pious” man who was not adorned with all moderation and virtue, or that a decorous man would utter such expressions as are contained in the unseemly iambics of Archilochus. And if nothing that is divine in itself is shown to belong either to the healing skill of Æsculapius or the prophetic power of Apollo, how could any one, even were I to grant that the facts are as alleged, reasonably worship them as pure divinities?— and especially when the prophetic spirit of Apollo, pure from any body of earth, secretly enters through the private parts the person of her who is called the priestess, as she is seated at the mouth of the Pythian cave! Whereas regarding Jesus and His power we have no such notion; for the body which was born of the Virgin was composed of human material, and capable of receiving human wounds and death.
Source: Against Celsus (New Advent)