Tertullian, Against Marcion 23

I set another rule before him: just as natural things are, so rational things ought to be in God. I demand a rational basis for goodness, because nothing else can count as good unless it is rationally good—much less can goodness itself be found irrational. It would be easier for evil, once some reason attaches to it, to pass as good than for good, deserted by reason, to escape being judged evil. I deny rational goodness to Marcion's God, first of all because he proceeded to the salvation of a foreign man. I know they will say this is the principal and perfect goodness, since it is poured out voluntarily and freely on strangers without any debt of kinship—precisely the standard by which we are commanded to love our enemies, who are already strangers to us by that very name. Why then did he not regard man from the beginning, from the beginning a stranger? By holding back, he prejudged that he had nothing to do with the stranger. Moreover, the discipline of loving a stranger or enemy preceded the command to love your neighbor as yourself. Even though that command comes from the Creator's law, you must accept it too, since Christ did not destroy it but built upon it. For the more you love your neighbor, the more you are commanded to love your enemy and the stranger. Exacting what is owed is an exaggeration of due goodness. But due goodness precedes undue goodness—as principal, as more worthy, as minister and companion to its own, that is, undue goodness, which comes first. Therefore, when the first reason for goodness is to show it to one's own out of justice, and the second is to show it to a foreigner out of the overflow of justice beyond the scribes and Pharisees, what kind of second reason can be assigned to one who lacks the first, who does not have his own man, and is therefore deficient? Furthermore, how did what is deficient, which never had its own, overflow into a foreigner? Produce the principal reason, and then vindicate the subsequent one. Nothing can be vindicated without rational order; so far is it from reason itself losing order in anything. Let the reason for goodness now begin from the second grade, namely toward the foreigner: nor will that second grade hold together rationally for him, since it has been destroyed another way. For only then will the second goodness toward a foreigner count as rational if it operates without injury to the one whose property it is. Whatever goodness justice first establishes is rational. Just as in the principal grade, when it is shown to one's own, it will be rational if it is just, so also toward a foreigner it can appear rational if it is not unjust. But what sort of goodness consists through injustice, and that for a foreigner? Perhaps injurious goodness might be considered rational to some extent for a household servant. But for a foreigner, to whom not even legitimate goodness is owed, by what reason can such unjust goodness be defended as rational? What is more unjust, more iniquitous, more wicked than to benefit a foreign servant in such a way that he is stolen from his master, claimed for another, and suborned against his master's head—and, what is more shameful, while still living in the master's house, eating from the master's stores, trembling under the master's blows? Such an advocate would be condemned even in the world, let alone the plagiarist. In no other way does Marcion's God, bursting into a foreign world, snatch man from God, son from father, pupil from teacher, servant from master, so that he makes him impious toward God, irreligious toward father, ungrateful toward teacher, wicked toward master. I ask you: if rational goodness produces such a man, what would irrational goodness produce? I cannot think of anyone more shameless than the one who is baptized in another's water for another god, ascends to another god's heaven, is laid out on another god's earth, offers thanksgiving over another's bread to another god, and operates with another's goods in the name of charity and love for another god. What kind of god is so good that man becomes evil from him, so favorable that he makes another god—indeed his own master—angry?