This hypothetical novel is set in a universe the inverse of ours: finite in size, but infinitely old (our cosmos being infinite in size and finitely old you see). How finite? The size of the medieval solar system, and bounded by a primum mobile. As our universe began with a big bang, and is a godless and material space, this universe has always existed in a steady state and is a godmade locale interpenetrated by spirit.
What happens in this novel? Well, in such a universe (though not in ours) there is an 'outside', topography beyond the boundary of things--though this outside is not quantifiable in the terms of the universe; and actually the 'side' and the 'out' that make up 'outside' are both features of the home universe as so do not properly obtain. So let's call it, rather, C. But creatures come into the universe from C; and they are us. The creatures we discover living in the innards os this shell resemble angels, or perhaps virtuous devils. The closer to the surface of a planet you go, the further removed you are from Grace, the substratum of this cosmos, and the more miserable you feel -- in this respect, it's like the Cosmos of Lewis's Ransom books. But even walking around on the surface of the planets the beings are more beautiful, stronger, cleverer, less prone to illness and so on. Nevertheless the novel takes a Dawkinsesque twist: it transpires that, having being created whole by a god, the one thing these entities are not so good at is surviving. The visitors, however, have been shaped by evolution; not only in the epiphenomenal manner of gradually upgraded physical and mental acuteness, but in the core sense ... every one of them (every one of us) is the end of a vastly long line of survivors. Every single one of our ancestors survived long enough to pass on its genes. There were countless other organisms in our reality that did not survive, but since they did not pass on their genes they have passed out.
'But,' the natives complain. 'We were created by God! We are perfect!'
'Of course that's exactly the problem,' one kindly-minded infodumper from the C-realm explains. 'Perfect is not an absolute term, or else a "perfect" being would be simultaneously perfectly tall and perfectly short, perfectly young and perfectly old. No, "perfect" only relates to a limited number of aspects of existence. In those respects you exceed us. But our inherent, evolution-granted survivability trumps all of them.'