"Do you believe in God?" [...]
"I'm waiting to" (4.177 - 4.178)
When Rachel asks her father Sol this question, he says that wants to believe, but that his scholarly knowledge is in direct opposition to his faith. It's strange that even though he's allegedly waiting for God, he doesn't see a God in the prophetic dreams he has.
The concept of a personal God, lying awake at night worrying about human beings [...] made [Sol] doubt his sanity. (4.537)
Sol's revelation about God is a lot like a kid's revelation about Santa Claus. Just how can he be in every house at once on Christmas Eve?
"The TechnoCore is trying to... what?... to build God" (5.791)
Building God, which seems to involve recreating the entire original planet Earth, is still probably easier than assembling the LEGO Star Wars Destroyer Droid. Hm: God as Earth sounds a lot like the Gaia hypothesis.