Serpent seed

===Early teachings===
[[Valentinus (Gnostic)|Valentinus]] (100–160) promoted a doctrine which is similar to the serpent seed doctrine because it states that Eve mated with the serpent and produced Cain. In his teaching, the serpent was the manifestation of an [[aeon]] named Sophia who seduced Eve. The teachings of Valentinus were compiled in the Gnostic [[Gospel of Philip]] ({{circa|350}}) where the idea that Eve mated with the serpent, or [[Satan]], and produced Cain, finds its earliest expression. A similar account is recorded in the Gnostic [[Apocryphon of John]] which was authored by the [[Sethians]] ({{circa|180}}).<ref>Byron, p. 18</ref>

{{blockquote
|text=First [[adultery]] came into being, afterward [[murder]]. And he (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. Indeed, every act of sexual intercourse which has occurred between those who are unlike one another is an act of adultery.
|source=Gospel of Philip 61:5-10
}}

[[Irenaeus]] recorded a portion of the teaching and denounced it as heresy in his book ''Against Heresies''.<ref name="autogeneratedix"/> Explaining and commenting on the teachings of Valentinus, Irenaeus states:

{{blockquote|text= [They] cunningly devised a scheme to seduce Eve and Adam, by means of the serpent ... this one (Eve) sinned by committing adultery ... Such are the opinions which prevail among these persons, by whom, like the Lernæan hydra, a many-headed beast has been generated from the school of Valentinus.
|title=''Against Heresies'' Chapter XXX.—Doctrines of the Ophites and Sethians.
|author=Irenaeus
}}