Do you have the Irenaeus and Hippolytus reference for this?
Both Irenaeus and Hippolytus described the heretical views of two Gnostic sects called the Ophites [FONT=&](from the Greek
ophis, "snake") and the Sethites.[/FONT] While neither one engaged in a point by point rebuttal of these Gnostics' teaching on the original human sin in Eden, they clearly did so in the context of refuting their overall schema.
Irenaeus:
[FONT=&]But their [/FONT][FONT=&][a family of deities] mother, Sophia, cunningly devised a scheme to seduce Eve and Adam, by means of the serpent, to transgress the command of Ialdabaoth [one of the “father” gods]. Eve listened to this as if it had proceeded from a Son of God, and yielded an easy belief. She also persuaded Adam to eat of the tree regarding which God had said that they should not eat of it. They then declare that, on their thus eating, they attained to the knowledge of that power which is above all, and departed from those who had created them. When Prunicus perceived that the powers were thus baffled by their own creature, she greatly rejoiced, and again cried out, that since the father was incorruptible, Ialdabaoth who formerly called himself the father was a liar; and that, while Anthropos and the first woman, the Spirit, existed previously, this one, Eve, sinned by committing adultery. Ialdabaoth, however, through that oblivion in which he was involved, and not paying any regard to these things, cast Adam and Eve out of Paradise, because they had transgressed his commandment. (Against Heresies, 1:30.7f; ANF 1:356)[/FONT]
Hippolytus:
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Baruch [/FONT][FONT=&][an archangel of the creator Elohim—i.e. the God of the Old Testament] then coming, stood in the midst of the angels of Edem [essentially “Mother Nature"], that is, in the midst of paradise—for paradise is the angels, in the midst of whom he stood,—and issued to the man the following injunction: “Of every tree that is in paradise thou mayest freely eat, but thou mayest not eat of the tree of the knowledge of good and evil,” which is Naas [Hebrew, Nachash, "the serpent”]. Now the meaning is, that he should obey the rest of the eleven angels of Edem for the eleven possess passions, but are not guilty of transgression. Naas, however, has committed sin, for he went in unto Eve, deceiving her, and debauched her; and such an act as this is a violation of law. He, however, likewise went in unto Adam, and had unnatural intercourse with him; and this is itself also a piece of turpitude, whence have arisen adultery and sodomy. (The Refutation of All Heresies, 5:21; ANF 5:71)[/FONT]
The basic idea is also present in the 4th Century Gnostic Gospel of Philip:
[FONT=&]First, adultery came into being, afterward murder. And he [/FONT][FONT=&][Cain] was begotten in adultery, for he was the child of the Serpent. So he became a murderer, just like his father, and he killed his brother [Abel]. Indeed, every act of sexual intercourse which has occurred between those unlike one another is adultery.[/FONT] (61:5-10)