How did you distinguish the Bible from, say, History?

By age 4 I think I had figured out that stories about magical or super-powerful beings always turned out to be made up. I did believe it when adults told me that people had souls though, until I got a book that showed the location of organs in the human body and I noticed it wasn't in there.

Well, what are your boundaries on "consider"? I remember entertaining the possibility of God's existence at a pretty early age -- somewhere between two and four, but infantile amnesia's eaten the specifics -- but always as a hypothetical, a playing-pretend game. It took me quite a while to realize that my peers weren't consciously participating in a pleasant fantasy; as late as age eight or so I remember making decisions that could only have been predicated on the opposite assumption.

For context, I was raised in a pretty obviously Christian cultural milieu -- picture books of Bible stories, a sense that it was normal to go to church on Sundays even if you and your parents didn't -- but most of my very early authority figures didn't make a conspicuous show of belief. "Secular" might be the word, but only implicitly so.

I also never took the idea of a real interventionist god seriously, and while I've only lived one childhood and so can't compare the effect of this influence to its absence, it might have had to do with the fact that I learned about dead religions at a very early age. By the time my fundamentalist grandmother started proselytizing to me at the age of three, I already had significant exposure to Greek mythology, and I mentally filed "Grandma's beliefs about God" into the same class as "Ancient Greeks' beliefs about gods." It didn't even occur to me until I was about eleven that these were beliefs I was expected to take seriously and have an emotional investment in.

I did experiment with the idea of a non denominational god as a kid, but I never felt the need to make excuses for the hypotheses if they turned up null results. I concluded that if there was a god, it wasn't giving me any reason to worship or believe in it, so I might as well assume it didn't exist.