Calculating God by Robert J. Sawyer (2000): Sawyer enjoyably stacks the deck to create a fictional universe where the existence of God is scientifically proveable.
A sarcastic, vaguely spider-shaped alien shows up at the Royal Ontario Museum in Toronto one day and asks to see a paleontologist. Cancer-stricken Thomas Jericho answers the call, and he and alien Hollus of the Forhilnors begin a three-way collaboration with another alien race, the Wreeds, to figure out what God is up to — and why technological civilizations keep disappearing.
This isn’t the God of any human holy text, admittedly — neither the Wreeds nor the Forhilnors believe that the creature is all-knowing or all-loving, but rather that it’s a massive intelligence from a previous universe that set the parameters of the current universe to allow life to develop.
Basically, God’s a lot like Galactus, but without all the planet-eating and cool-helmet-wearing.
The best parts of this novel are the lengthy sections of dialogue in which various scientific theories are debated. A sub-plot involving abortion-clinic bombers is mostly unfortunate (especially as Sawyer comically names one of them ‘Cooter’).
The conclusion starts off interestingly cosmic and then comes up with something that answers a biological puzzle without necessarily making sense once one thinks about it for awhile. Still, a fast-paced, enjoyable read, set pretty much entirely in Canada and in space. Recommended.