II.2 chapter 3

So how can there be that are called enemies of God?
They withstand the commandement of God, but do not harm God by doing that, but themselves (because God is unchangeable and incorruptable). Their vice is contrary to their nature, and therefore contrary to the good and thus contrary to God (which is the supreme good); but the vice doesn't harm God like it harms their nature. For to God no evils are harmful; they only harm the changeable and corruptable natures.

Something evil is always something harmful. Indeed the concept 'evil' means that it is contrary to something good. 'Evil' is no concept for something substantial, but for something depriving something of good, something that therefore has good nature.

But does the punishment of someone vicious do anything good to their existence?
Because that punishment is just, it is good. It is just because every such vice originates in the will, 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 we are speaking of natures that have a mental capacity for that enlightenment which discriminates between what is just and what is unjust).

II.2 chapter 2

So evil, as we already stated, is not something of a different source standing opposite to God. It can be understood easily because being is the nature of God (as the words 'I am: that I am' ('ego sum, qui sum') mean). God has most being, but everything that is made has a grade of being (some more, some less) given to them by God: therefore nothing stands opposite to God (nothing except something what would not be: so nothing).

II.2 chapter 1

We will first speak of the common division between angels and between man, how there are only two 'cities' because bad and good wills are separated the same.

We already mentioned that the holy angels and fallen angels are separated by their good or bad will, not by their nature, because God created them.
How is an evil will related to the misery of their state?
Because God is everything, and angels and man alike were created out of nothing, it is easy to see that angels and man cannot have their blessedness from their own nature ('quia ex nihilo creata est'), but must have it from God ('ex illo, a quo creata est'). (As we already stated that the only source of evil is deprivation of the good which is in God.)

But doesn't this make angels and man more wretched than other things because they can lose their blessedness?
Indeed only God cannot lose his blessedness because he has that blessedness in himself; however, angels and man that have their blessedness from God and therefore are changeable, are of a very good nature because they can share in the supreme good from God which is unchangeable. They exceed things which cannot feel anything and from nature cannot share in the highest good from God, also when they can become miserable: nobody would follow the same pattern of reasoning saying another member of the body is better than the eye because it cannot be blind. Even the fact that we call evil a vice proves that it is a good nature that was deprived.