Summa contra Gentiles3.140 Chapter CXL. That man’s actions are punished or rewarded by God

It is clear from the foregoing that man’s actions are punished or rewarded by God. Because to punish or reward belongs to him who imposes the law: since legislators induce men to obey the law, by rewards and punishments. Now, as we have shown above, it belongs to divine providence to set a law for men. Therefore it belongs to God to punish or reward men.

Again. Wherever a certain order is requisite to an end, that order must needs lead to that end, and infringement of that order debars from it: since those things that are on account of the end, take their necessity from the end; so that, to wit, they are necessary, if the end has to follow; and, given them, if there be no obstacle, the end will follow. Now, God appointed to man’s actions a certain order in relation to the end of the good, as we have already proved. Consequently, given that this order is rightly followed, those who comply with it attain the end of good, which consists in being rewarded: while those who forsake that order through sin, are debarred from the end of good, which is to be punished.

Also. As natural things are subject to the order of divine providence, so too are human acts, as we have shown. In either case, the due order may happen to be observed or disregarded: but there is this difference, that observance or disregard of the due order, is left in the power of the human will: whereas it is not in the power of natural things to deflect from the right order, or to follow it. Now, between effect and cause there should be a certain fitting correspondence. Wherefore, as when the requisite order of natural principles and actions obtains in natural things, the result is that, of necessity, their nature is sustained, and their good ensured, whereas corruption and evil result in them, when the natural and requisite order is not observed; so too in human affairs it must needs be that, when man voluntarily keeps the order of the law imposed by God, a good accrues to him, not of necessity as it were, but by the appointment of his Lord; and this is to be rewarded: and conversely, that his lot is evil, when the order of the law has been infringed; and this is to be punished.

Besides. It belongs to God’s goodness that he leaves nothing out of order: hence we may observe in natural things, that every evil is contained in the order of some good: thus corruption of the air is generation of fire, and the slaying of the sheep is the meal of the wolf. Since, then human acts are subject to divine providence, even as natural things are: it follows that whatever evil occurs in human actions must be included in the order of some good. This is most fittingly done in the punishment of sins. For thus things that exceed in due quantity are included in the order of justice, which reduces them to equality. Now, man exceeds the mark of his right quantity, when he prefers his own will to God’s, by gratifying it against the divine ordinance. And this inequality is removed when, against his will, man is compelled to suffer something according to the divine ordinance. Therefore man’s sins need to be punished by God: and for the same reason his good deeds should be rewarded.

Further. Divine providence not only appoints the order of things, but also moves all things to the execution of the order by himself appointed, as we have already proved. Now, the will is moved by its object, which is either good or evil. Hence it belongs to divine providence, to set good things before man as his reward, that his will may be moved to proceed aright; and to set evil things before him as his punishment, that he may avoid falling out of order.

Moreover. Divine providence has ordered things in such wise that one is of profit to another. Now, it is most fitting that a man should advance to the end of good, both through the good and through the evil of another man, in that he is urged to do well through seeing that well-doers are rewarded, and is recalled from evil doing, through seeing that evil-doers are punished. Therefore it belongs to divine providence that the wicked be punished, and the good rewarded.

This is what is said (Exod. xx. 5, 6): I am... thy God... visiting the iniquities of the fathers upon the children... and showing mercy... to them that love Me, and keep My commandments. Also in the psalm: Thou wilt render to every man according to his works. Again (Rom. ii. 6, 8): Who will render to every man according to his works. To them indeed, who, according to patience in good work... glory and honour: but to them that... obey not the truth, but give credit to iniquity, wrath and indignation.

Hereby we refute the error of some who said that God punishes not. For Marcion and Valentine said that the God who is good is another from the God who is just, and punishes.