Homilies on the Psalms, p. 313.
All right, look at what they say: “The creator is savage, the creator is inhumane, there is another, higher, good god.”
Here is the footnote:
In Hom. Jer. 1.16, Origen also says that heretics call the god who gave the Mosaic law “savage” and “inhumane” (agrios and apanthrōpos). They do so because they fail to recognize that Scripture has a deeper sense. Simpler Christians are guilty of the same fault. In Princ. 4.2.1 Origen commends simpler Christians for understanding that there is no higher God than the creator (dēmiourgos), but accuses them of believing worse things about God than one would believe about the most bloodthirsty and unjust of human beings.
It's possible that these words (agrios, apanthrōpos, and dēmiourgos) were in Marcion's Antitheses.