we had sat through a sermon where the preacher talked about some awful furriners in one of them awful furrin' countries where they believed in a religion other than The One True Religion. Being somewhat naive at the time, I was confused and upset by these dark revelations, and asked my mother why people would believe in some religion which was obviously wrong. She just said "I guess they were raised that way." I had expected something more devious, more subtle, more nefarious, and was a bit let down that it should be something so simple and seemingly innocent. And of course I realized almost immnediately that we believed in our own religion because we were raised that way -- not because of some profound truths unique to that religion, or because it was logically more convincing, or more favored by the evidence -- but just because we had been born into that particular religion, passed down from parent to child in that family for generations, without question. What applied to those people in the sermon applied just as well to us.
Strangely, this occurred when I was still young enough to believe in Santa Claus, the Easter Bunny, and the Tooth Fairy. By the time those were all revealed to be lies (WHY do parents find it amusing to lie to their children? And why is it considered a hallowed tradition?) my faith was pretty weak, and by the time I was 10 or so I had concluded that the stories in the Bible were no more believable than the Greek, Norse, or Amerindian myths and legends I had read in school (see, education is dangerous!). It seemed to me that atheism made more sense than all the religions of the world put together, and I couldn't understand why everyone around me still clung to their god long after they had outgrown Santa Claus, Thor, etc. It struck me as not wanting to mature, to think like intelligent adults, to declare one's independence from primitive beliefs in magical sky beings. It still does.