After this, being desirous to show that it is nothing either wonderful or new which we state regarding floods or conflagrations, but that, from misunderstanding the accounts of these things which are current among Greeks or barbarous nations, we have accorded our belief to our own Scriptures when treating of them, he writes as follows: “The belief has spread among them, from a misunderstanding of the accounts of these occurrences, that after lengthened cycles of time, and the returns and conjunctions of planets, conflagrations and floods are wont to happen, and because after the last flood, which took place in the time of Deucalion, the lapse of time, agreeably to the vicissitude of all things, requires a conflagration and this made them give utterance to the erroneous opinion that God will descend, bringing fire like a torturer.”
Now in answer to this we say, that I do not understand how Celsus, who has read a great deal, and who shows that he has perused many histories, had not his attention arrested by the antiquity of Moses, who is related by certain Greek historians to have lived about the time of Inachus the son of Phoroneus, and is acknowledged by the Egyptians to be a man of great antiquity, as well as by those who have studied the history of the Phœnicians. And any one who likes may peruse the two books of Flavius Josephus on the antiquities of the Jews, in order that he may see in what way Moses was more ancient than those who asserted that floods and conflagrations take place in the world after long intervals of time; which statement Celsus alleges the Jews and Christians to have misunderstood, and, not comprehending what was said about a conflagration, to have declared that “God will descend, bringing fire like a torturer.”
Source: Against Celsus (New Advent)