(The following thoughts are inspired by Barry's much-appreciated comments on previous posts.)
Let's start with this observation, commonly associated with Jean Piaget but now generally accepted by most child psychologists, that the explanations of children across all cultures are initially artificialist: that is, objects or events are understood as the product of a humanlike agency. Thus, the sun was made to provide light for us. A tree was made to give shade. "Why is the stone round?" asks the psychologist. "Because it was made that way," responds the child. Making requires a maker. At first, the child is unspecific about who that maker might be, but culture soon provides an answer: the gods or God.
Why are a children artificialists? There may be something innate about it, as some evolutionary psychologists suggest (Dean Hamer thinks he has identified a gene for self-transcendence), but it seems to me an adequate reason can be found in the infant's initial experience. A newborn human is helpless. Food, warmth, affection, lullabies, light, shade and every other material and emotional requirement of life are provided by a provident parent. What could be more natural than that the default human explanation is artificialist? Is it any surprise that we call God father or mother, or that the gods in every culture are represented in human guise? (Even animal gods have human personalities.)
A comet appears in the sky, unheralded and unexplained: It is a sign from God. A disease ravages a city: It is God's punishment. A fine soft day, thanks be to God, say the Irish. And so does the experience of the infant carry over into adulthood.
Newtonian physics provided a naturalistic, non-artificialist way to account for comets. The germ theory of disease explains epidemics without invoking a deity. Darwin's theory of evolution by natural selection pushed artificialism out of the story of life. And so do we put behind us the biologically inculcated default explanations of the child.
There remain, of course, things or events we cannot yet explain. Why is there something rather than nothing? What came before the big bang? How did life begin? What is the biological basis of self-awareness? The default answer to these questions for the vast majority of humans remains artificialist: God. The alternate response is not atheism, which is no explanation at all. The alternate response is: "I don't know."
If the history of science teaches us anything, it is that behind the artificialist explanations of our ancestors there are patterns of order that go far to help us understand the world. And no gift of science is more important to our maturity as a species than permission to admit our ignorance.