Abstract The biblical argument plays a considerable role in Julian’s controversy against Christianity and has certainly contributed to the “invincible efficiency” of his work, as pointed out by his adversary Cyril of Alexandria. This paper focuses on two verses Gen 49:10 and Gen 6:2 invoked by Julian to prove that Moses has never spoken, either of the coming of Jesus, or of an Only-Begotten Son of God, and consequently that Christians are unfaithful to Moses. The specificity of this debate is that it concerns not only the interpretation of these verses, but the very form of the biblical text, its possible falsification or the existence of marginalia. In this second case, Cyril’s refutation in his Contra Julianum , as well as parallels in other Cyrillian works, helps to understand that Julian is referring to a biblical paratext, a rare element that enhances his reputation as a good connoisseur of the exegetical debates of his time, and provides a particularly interesting testimony about the material transmission of the biblical text.