7 But I will merely say, in opposition to these men — Did all those who have been mentioned, with whom you have been proved to coincide in expression, know, or not know, the truth? If they knew it, then the descent of the Saviour into this world was superfluous. For why [in that case] did He descend? Was it that He might bring that truth which was [already] known to the knowledge of those who knew it? If, on the other hand, these men did not know it, then how is it that, while you express yourselves in the same terms as do those who knew not the truth, you boast that yourselves alone possess that knowledge which is above all things, although they who are ignorant of God [likewise] possess it?
Thus, then, by a complete perversion of language, they style ignorance of the truth knowledge: and Paul well says [of them,] that [they make use of] “novelties of words of false knowledge.” For that knowledge of theirs is truly found to be false. If, however, taking an impudent course with respect to these points, they declare that men indeed did not know the truth, but that their Mother, the seed of the Father, proclaimed the mysteries of truth through such men, even as also through the prophets, while the Demiurge was ignorant [of the proceeding], then I answer, in the first place, that the things which were predicted were not of such a nature as to be intelligible to no one; for the men themselves knew what they were saying, as did also their disciples, and those again succeeded these.
And, in the next place, if either the Mother or her seed knew and proclaimed those things which were of the truth (and the Father is truth), then on their theory the Saviour spoke falsely when He said, “No one knows the Father but the Son,” unless indeed they maintain that their seed or Mother is No-one.
Source: Adversus haereses (New Advent)