Origen attempts to undermine Celsus's credibility first by labelling him an Epicurean, since, by the third century, Epicureanism was almost universally seen as discredited and wrong, because of its teachings of materialism, its denial of divine providence, and its hedonistic teachings on ethics. Nonetheless, Origen stops calling Celsus an Epicurean about halfway throughout the text, possibly because it was becoming increasingly difficult to present him as such in light of Celsus's self-evident sympathies for Plato. Origen also attempts to undermine Celsus's credibility by pointing out his ignorance on particular issues. In two cases, Origen points out problems in the literal interpretations of Biblical passages that Celsus himself had overlooked: the contradictory genealogies of Jesus given in the Gospels of Matthew and Luke, and the impossibility that Noah's Ark, if built according to the supposed measurements given in the Book of Genesis, could have held all the animals it is supposed to have held. Based on these examples, Origen attempts to show that Celsus's criticism is based on too literal interpretation of the Bible and therefore flawed. Origen also employs his training in textual analysis to question the integrity of Celsus's Jewish source. Origen points out that the supposed "Jewish" source refers to Old Testament prophecies that do not really exist, indicating that the author was unfamiliar with the Hebrew Bible. He also notes with suspicion that the "Jewish" source quotes the Greek tragedian Euripides and that it argues against the miracles described in the New Testament as irrational, even though the same argument could be equally applied to the miracles in the Hebrew Bible.
