Tertullian, Against Marcion 30

How did he handle the question about healing on the Sabbath? "Doesn't each of you on the Sabbath untie his donkey or ox from the manger and lead it to water?" (Luke 13:15). So, acting in line with the law's own condition, he upheld the law; he did not dissolve it. The law commands that no work be done except what is done for the sake of any soul, how much more a human one? I see that the coherence of parables is required everywhere. "The kingdom of God is like a mustard seed, which a man took and sowed in his garden" (Luke 13:19). Who is meant by the man? Obviously Christ, who, even on Marcion's terms, is called the Son of Man. He received the seed of the kingdom from the Father — that is, the gospel message — and sowed it in his garden, which is this world. Suppose the 'man' is a human being; but since he said 'in his garden,' and neither the world nor the man belongs to the alien god but to the Creator, the one who sows in his own domain is shown to be the Creator's agent. Or if, to escape this trap, they shift the 'man' from Christ to a believer receiving the seed of the kingdom and sowing it in the garden of his heart, even that soil suits no one but the Creator.

I dread the next plain similitude, lest it betray the kingdom of another god. He compared it to leaven, not to unleavened bread, which is more familiar to the Creator. This conjecture suits those begging for arguments just fine. So I will drive out vanity with vanity and say fermentation fits the Creator's kingdom too, because after it comes the oven or furnace of Gehenna. What kind of kingdom belonging to a supremely mild god is followed by the fury of judgment with tearful severity? How often does he still show himself as a judge, and in the judge reveal the Creator? How often does he reject and condemn by rejecting? Just like here: "When the master of the house rises" — where? Nowhere but where Isaiah said: "When he rises to shake the earth" — "and shuts the door" (Luke 13:25), certainly to exclude the wicked. When they knock, he will answer, "I don't know where you're from," and again, when they list what they ate and drank in his presence and taught in their streets, he will add: "Depart from me, all you workers of iniquity" (Luke 13:27; Matthew 24:51). There will be weeping and gnashing of teeth — where? Outside, obviously, where they are excluded by the shut door. So the punishment comes from the one who executes the exclusion into punishment. "When they see the righteous entering the kingdom of God, but themselves thrown outside" (Luke 13:28). From whom? If from the Creator, who then is inside receiving the righteous into the kingdom? The 'good' god? What is the Creator doing there, then? Detaining in punishment outside those whom his adversary excluded? They would be received by him, if anything, rather in the adversary's spite. But the one who is about to exclude the wicked must surely know that the Creator will detain them in punishment — or he ought not to know. Therefore either they are detained against his will, and the one who detains is inferior to him, yielding to him unwillingly, or if he wants it that way, he himself has judged it so. And he will be no better than the Creator, since he becomes the author of the Creator's infamy. If these things hold together by no logic at all, so that one is supposed to punish and another to liberate, then both the judgment and the kingdom belong to one God. And since both belong to one, the one who judges is the Creator's.