Well the stories are older, they've been told they are true for their entire lives. Religious types like to act as though something is true until proven false which explains the misdirection of their attacks on evolution, always pointing out the gaps but not touching the voluminous supporting evidence.
Now that more and more archaeologists have been given access to the Holy lands we're finding out more and more that the events described int he bible may have had some historical basis, but are highly embellished, some of the time lines are even off by centuries.
Of course there are a lot of biblical stories for which there is absolutely no evidence, and it is highly doubted that any evidence will ever be found. What has never been found is any evidence of anything remotely approaching "supernatural", the geologic record shows there was never a global flood (although the story could be based on a more local flooding).
What we have in the bible, as in most holy texts are parables, fables, folklore and "entertaining stories" designed to help the citizens of a technological society pass down traditions, laws and history. That ANYONE takes them literally is a sign of simple people who need simple explanations. "It can't be a metaphor because I don't understand the metaphor, so it must have really happened that way".
Read "Mistakes Were Made...But Not by Me" by Carol Tarvis and Elliot Aronson. Everything will be oh-so-clear. And it is also a very frustrating book because ti makes you question pretty much everything you think or do.
Another reason'll be that MacBeth doesn't claim to be god c.c
Anyone who knows how actually think, and uses their brains to do it, will realise that the stories in the bible are just that, stories, but because of all the pretty miracles and magic, some people like to think it's real.
The pretty stories give people a reason to think they are special and some pretty stories about what may happen when they die. So it's a comfort thinga nd an arrogance thing.
How many people would CHOOSE religion if we (as a culture) insisted that a minor had to be at least 16 years of age before picking/being exposed to a religion or not? Being brought up in the church is basically institutionalized indoctrination which is not only accepted, but in many cases encouraged by our culture. Break that first step and you'll see a huge disbelief rate in the first generation.
If I had to take a stab at that question, my answer would be that people are conditioned from childhood into believing the bible to be true because there parents said so, and then they see other adults telling them the same thing, and there are few if any that says different. Then they are taught that the bible shouldn't be questioned, and that they are given Pascals wager, and if that isn't good enough, they would be ostracized. They same would be true if you were taught that a rotten cabbage is god.
If I had to select a holy book as a reference for humanity it would be Lord of the Rings. As a guide to ethics, morals, virtue and human decency, it shits all over anything else we have. This is not not serious. Just an observation I made as a kid that has been reaffirmed over the 15-20 times I have re-read the thing.