City of God

In Scripture they are called God's enemies who oppose His rule, not by nature, but by vice; having no power to hurt Him, but only themselves. For they are His enemies, not through their power to hurt, but by their will to oppose Him. For God is unchangeable, and wholly proof against injury. Therefore the vice which makes those who are called His enemies resist Him, is an evil not to God, but to themselves. And to them it is an evil, solely because it corrupts the good of their nature.

It is not nature, therefore, but vice, which is contrary to God. For that which is evil is contrary to the good. And who will deny that God is the supreme good? Vice, therefore, is contrary to God, as evil to good. Further, the nature it vitiates is a good, and therefore to this good also it is contrary. But while it is contrary to God only as evil to good, it is contrary to the nature it vitiates, both as evil and as hurtful. For to God no evils are hurtful; but only to natures mutable and corruptible, though, by the testimony of the vices themselves, originally good.

For were they not good, vices could not hurt them. For how do they hurt them but by depriving them of integrity, beauty, welfare, virtue, and, in short, whatever natural good vice is wont to diminish or destroy? But if there be no good to take away, then no injury can be done, and consequently there can be no vice. For it is impossible that there should be a harmless vice. Whence we gather, that though vice cannot injure the unchangeable good, it can injure nothing but good; because it does not exist where it does not injure.

This, then, may be thus formulated: Vice cannot be in the highest good, and cannot be but in some good. Things solely good, therefore, can in some circumstances exist; things solely evil, never; for even those natures which are vitiated by an evil will, so far indeed as they are vitiated, are evil, but in so far as they are natures they are good. And when a vitiated nature is punished, besides the good it has in being a nature, it has this also, that it is not unpunished. For this is just, and certainly everything just is a good.

For no one is punished for natural, but for voluntary vices. For even the vice which by the force of habit and long continuance has become a second nature, had its origin in the will. For at present we are speaking of the vices of the nature, which has a mental capacity for that enlightenment which discriminates between what is just and what is unjust.