RLK: [...] One of the things we are told [about God] is that he is perfectly free [....] To be perfectly free, to us, mean you can do anything. [...] But we know there are certain thing God can't do: God can't sin. [...] How should I think about this?
Oliver Crisp: [...] Minimally I want to say, "God is free" means that God acts in accordance with his character. And because he has a certain kind of character or nature, he can do certain sorts of things and can't do other things. You've already mentioned that he can't sin. Right, so there are certain things that are outside of his nature, that wouldn't be in accordance with his nature. So we might think of his nature, in a kind of rough and ready sense, as a kind of restraint on what God can do. Therefore, it would be false to think God could create a world full of evil, or full of disaster and tragedy that is unreleased and wouldn't come out to some greater good. That would seem to be inconsistent with the divine nature. Just as I would be against the divine nature to create or to do something that is wicked.
Nevertheless we want to say in some robust sense that he is free. Free to create a world; he is free to refrain from creating a world. There mustn't be the case that God must create a world. Although there are some Christian theologians that have thought that. [...]
When we talk about divine freedom, we want to say that God could have refrained from creating the world and still have been infinitely happy. Nevertheless as an act of free grace he does create a world.