The Five Books Against Marcion by Tertullian
Chapter XXIII.--God's Purposes in Election and Rejection of the Same Men, Such as King Saul, Explained, in Answer to the Marcionite Cavil.
Now, although you will have it that He is inconstant in respect of persons, sometimes disapproving where approbation is deserved; or else wanting in foresight, bestowing approbation on men who ought rather to be reprobated, as if He either censured His own past judgments, or could not forecast His future ones; yet nothing is so consistent for even a good judge as both to reject and to choose on the merits of the present moment. Saul is chosen, but he is not yet the despiser of the prophet Samuel. Solomon is rejected; but he is now become a prey to foreign women, and a slave to the idols of Moab and Sidon. What must the Creator do, in order to escape the censure of the Marcionites? Must He prematurely condemn men, who are thus far correct in their conduct, because of future delinquencies? But it is not the mark of a good God to condemn beforehand persons who have not yet deserved condemnation. Must He then refuse to eject sinners, on account of their previous good deeds? But it is not the characteristic of a just judge to forgive sins in consideration of former virtues which are no longer practised. Now, who is so faultless among men, that God could always have him in His choice, and never be able to reject him? Or who, on the other hand, is so void of any good work, that God could reject him for ever, and never be able to choose him? Show me, then, the man who is always good, and he will not be rejected; show me, too, him who is always evil, and he will never be chosen. Should, however, the same man, being found on different occasions in the pursuit of both (good and evil) be recompensed in both directions by God, who is both a good and judicial Being, He does not change His judgments through inconstancy or want of foresight, but dispenses reward according to the deserts of each case with a most unwavering and provident decision.