@Glyph: that's great. I've encountered the general idea of ordered levels of reality before (e.g. Flatland, Heidegger, Anathem,
these SMBC's), but I haven't seen that take on it. I'll have to think about it a bit. One question that occurs to me right away is what distinguishes "natural" from "artificial" universes, but I'll have to consider it a bit more.
You have not actually told us why you believe though,
If God did not create us, who did?
Ninja'd by Fenrir, but here is my take.
Is an agent (a "who") necessary for our creation?
Order does, under some conditions, arise out of chaos. The laws of our universe are such that spontaneous organization does occur from time. For example, the condensation of stars, galaxies, galaxy clusters, etc... all occur as a result of fundamental physical laws. On a terrestrial level, we see the formation of water vapor into clouds and the crystalization of organic and inorganic molecules into gems. Very plausabily, naturally occuring amino acids might have latched onto one another, as they are wont to do, which triggered further latching and replication of this patern. Ants form colonies capable of greater feats than the sum of its parts, fish and cows gather to form heards, and people organize themselves into artifical entities like corporations and states.
I do not see the necessity for a personality to "create" each of these things, the rules and order of the universe are sufficient to allow the emergence of clouds, people, and nations.
On the other hand, the beauty of these laws, the regularity and
knowability of the universe seem to indicate a deeper design. Perhaps physics can explain people, but how do we explain the regularity and beauty of physics itself? This seems a much more compelling argument to me. However, this type of "watchmaker" god also seems inconsistent with the miracles and divine intervention of the Christian God, and so this idea has done little to draw me in that direction.