The Bible Test
Perhaps an intelligent force helped guide the Bible's writers to test the character of its readers. The three main approaches to the Bible are: it is 100% true and moral, or the supernatural exists (including being part of a simulation) but some of the stories weren't historical, or the supernatural doesn't exist.
I think there are good reasons to believe each of these possibilities though any seemingly supernatural events are likely to be explained by coincidence, delusion, or hallucinations.
Option 1: The Bible is 100% true and moral
This means that God is perfectly just and loving, even if most people are going to hell, perhaps forever. The faith of a child is praised, while "the wisdom of this world is foolishness in God's sight" (1 Corinthians 3:18-19). With a plain reading of the Bible it seems the world was created a few days before humans were. The Bible also seems to say the Earth is flat and no verses are against this (see counter arguments).
From Answers in Genesis:
"Ultimately, the controversy about the age of the earth is a controversy about the authority of Scripture. If millions of years really happened, then the Bible is false and cannot speak with authority on any issue, even the Gospel."
If Christians have this all-or-nothing kind of thinking they can go from believing that the universe is about 6000 years old to becoming an atheist. That is what happened to me. This comic talks about this: The Dark Side of Young Earth Creationism
Option 2: The Bible isn't straight-forward
Some Christians don't believe that everything in the Bible is literal history. For example the six days of creation in Genesis have a kind of poetic structure known as the framework interpretation:
|First Triad||Second Triad|
|Let there be light - and day and night||Let there be lights to rule the day and night|
(sun / moon / stars)
|Waters and sky||Sea creatures and birds||Day
|Land and vegetation||Land animals and humans||Day
Young Earth Creationists believe that the sun, moon, and stars were literally created one day after the trees. Old Earth Creationists have a more complicated approach. Note that it is possible that all-or-nothing thinking isn't true - perhaps reality isn't consistent - like in games where there are "cheats".
Option 3: The Bible has no supernatural basis
Atheists might reason that since 2 Timothy 3:16 says "All Scripture is God-breathed", if God is real then the Bible should be 100% true. While atheists can be open to evidence that God exists, the Bible says to not put God to the test. This lack of evidence can make atheists conclude that God is a fairy tale.