12 And not among the heathen only did the devil make these assaults; for many of those who are falsely called Christians, and wrongfully addressed by the sweet name of Christ, have ere now impiously dared to banish God from His own creation. I mean the brood of heretics, those most ungodly men of evil name, pretending to be friends of Christ but utterly hating Him. For he who blasphemes the Father of the Christ is an enemy of the Son. These men have dared to speak of two Godheads, one good and one evil! O monstrous blindness! If a Godhead, then assuredly good. But if not good, why called a Godhead? For if goodness is an attribute of God; if loving-kindness, beneficence, almighty power, are proper to God, then of two things one, either in calling Him God let the name and operation be united; or if they would rob Him of His operations, let them not give Him the bare name.
Source: Catechetical Lectures (New Advent)