Incidentally Origen felt no need to believe that 'Adam and Eve' were a strictly literal account.
http://www.newadvent.org/fathers/04164.htm
For as those whose business it is to defend the doctrine of providence do so by means of arguments which are not to be despised, so also the subjects of Adam and his son will be philosophically dealt with by those who are aware that in the Hebrew language Adam signifies man; and that in those parts of the narrative which appear to refer to Adam as an individual, Moses is discoursing upon the nature of man in general. For in Adam (as the Scripture says) all die, and were condemned in the likeness of Adam's transgression, the word of God asserting this not so much of one particular individual as of the whole human race. For in the connected series of statements which appears to apply as to one particular individual, the curse pronounced upon Adam is regarded as common to all (the members of the race), and what was spoken with reference to the woman is spoken of every woman without exception. And the expulsion of the man and woman from paradise, and their being clothed with tunics of skins (which God, because of the transgression of men, made for those who had sinned), contain a certain secret and mystical doctrine (far transcending that of Plato) of the souls losing its wings, and being borne downwards to earth, until it can lay hold of some stable resting-place.
Celsus was already aware of allegorical interpretation of the Genesis accounts.
In the next place, as if he had devoted himself solely to the manifestation of his hatred and dislike of the Jewish and Christian doctrine, he says: The more modest of Jewish and Christian writers give all these things an allegorical meaning; and, Because they are ashamed of these things, they take refuge in allegory.
But:
If Celsus had read the Scriptures in an impartial spirit, he would not have said that our writings are incapable of admitting an allegorical meaning.
And we shall adduce a few instances out of very many to show that Celsus brings an empty charge against the Scriptures, when he says that they are incapable of admitting an allegorical meaning. Paul, the apostle of Jesus, says: It is written in the law, You shall not muzzle the mouth of the ox that treads out the grain. Does God take care for oxen? Or says He it altogether for our sakes? For our sakes, no doubt, this is written, that he that ploughs should plough in hope, and he that threshes in hope of partaking. And in another passage the same Paul says: For it is written, For this cause shall a man leave his father and mother and shall be joined to his wife, and they two shall be one flesh. This is a great mystery; but I speak concerning Christ and the Church. And again, in another place: We know that all our fathers were under the cloud, and all passed through the sea; and were all baptized unto Moses in the cloud, and in the sea. Then, explaining the history relating to the manna, and that referring to the miraculous issue of the water from the rock, he continues as follows: And they did all eat the same spiritual meat, and did all drink the same spiritual drink. For they drank of that spiritual Rock that followed them, and that Rock was Christ. Asaph, moreover, who, in showing the histories in Exodus and Numbers to be full of difficulties and parables, begins in the following manner, as recorded in the book of Psalms, where he is about to make mention of these things: Give ear, O my people, to my law: incline your ears to the words of my mouth. I will open my mouth in parables; I will utter dark sayings of old, which we have heard and known, and our fathers have told us.
Again Celsus:
Celsus appears to me to have heard that there are treatises in existence which contain allegorical explanations of the law of Moses. These however, he could not have read; for if he had he would not have said: The allegorical explanations, however, which have been devised are much more shameful and absurd than the fables themselves, inasmuch as they endeavour to unite with marvellous and altogether insensate folly things which cannot at all be made to harmonize. He seems to refer in these words to the works of Philo, or to those of still older writers, such as Aristobulus. But I conjecture that Celsus has not read their books, since it appears to me that in many passages they have so successfully hit the meaning (of the sacred writers), that even Grecian philosophers would have been captivated by their explanations; for in their writings we find not only a polished style, but exquisite thoughts and doctrines, and a rational use of what Celsus imagines to be fables in the sacred writings.
After this, selecting from all the treatises which contain allegorical explanations and interpretations, expressed in a language and style not to be despised, the least important, such as might contribute, indeed, to strengthen the faith of the multitude of simple believers, but were not adapted to impress those of more intelligent mind, he continues:
Of such a nature do I know the work to be, entitled Controversy between one Papiscus and Jason, which is fitted to excite pity and hatred instead of laughter. It is not my purpose, however, to confute the statements contained in such works; for their fallacy is manifest to all, especially if any one will have the patience to read the books themselves. Rather do I wish to show that Nature teaches this, that God made nothing that is mortal, but that His works, whatever they are, are immortal, and theirs mortal. And the soul is the work of God, while the nature of the body is different. And in this respect there is no difference between the body of a bat, or of a worm, or of a frog, and that of a man; for the matter is the same, and their corruptible part is alike.
Nevertheless I could wish that every one who heard Celsus declaiming and asserting that the treatise entitled Controversy between Jason and Papiscus regarding Christ was fitted to excite not laughter, but hatred, could take the work into his hands, and patiently listen to its contents; that, finding in it nothing to excite hatred, he might condemn Celsus out of the book itself. For if it be impartially perused, it will be found that there is nothing to excite even laughter in a work in which a Christian is described as conversing with a Jew on the subject of the Jewish Scriptures, and proving that the predictions regarding Christ fitly apply to Jesus; although the other disputant maintains the discussion in no ignoble style, and in a manner not unbecoming the character of a Jew.
http://www.earlychristianwritings.com/aristo.html
http://www.earlychristianwritings.com/text/aristo.html
http://en.wikipedia.org/wiki/Dialogue_o ... d_Papiscus
In 2012 a fragment was published of this text in HTR:
http://journals.cambridge.org/action/di ... 6012000211
"... almost every critical biblical position was earlier advanced by skeptics." - Raymond Brown