When, therefore, Marcion or some one of his hounds barks against the Demiurge, and adduces reasons from a comparison of what is good and bad, we ought to say to them, that neither Paul the apostle nor Mark, he of the maimed finger, announced such (tenets).
http://www.newadvent.org/fathers/050107.htm
And still, the explicit Marcionite dogma that Jesus is not Good:
And He has, he says, been liberated from the nature of the Good One likewise, in order that He may be a Mediator, as Paul states,Galatians 3:19 and as Himself acknowledges: Why do you call me good? There is one good,
That marcionite dogma is reported also by Epiphanius:
But again, let’s devote our attention to their other arguments. For they say in turn, though they do not have a sound understanding of the text, that the Savior himself said, “Why callest thou me good? There is one good, God,” 242 and thereby separated himself from the essence and subsistence of the Father.
https://archive.org/stream/EpiphaniusPa ... 1_djvu.txt