It is simple. We can believe in God, but there is no way to objectively demonstrate the existence of non-existent of any god. People can, based on a body of evidence and reasoning, determine subjectively they have no reason to believe. But knowing that a god exists or does not is an impossibility.
I would bet that your reasons for believing are much as mine, it is faith-based and there may be some subjective reason(s) that you cannot demonstrate. Probably the biggest factor is because you were raised in that culture.
For years, I used to believe in the Bible without question, including the Genesis creation and flood narratives. From the time my sister joined her church and given me my first bible to read, when I was 14 or 15, to when i was 34 in 2000.
During that time, I never thought of comparing science or history/archaeology with the Bible.
But it wasn’t history or science that first made me change my view, when I was 34.
2000 was my 2nd year building my website Timeless Myths, and I was doing research on Joseph of Arimathea, for my grail pages, that I re-read the gospels that I noticed the discrepancies that I didn’t see earlier, in the story of Jesus’ birth, particularly the gospel’s quote of Isaiah’s sign, Immanuel.
When I first read the Bible, from cover to cover, I didn’t know the gospel has taken Isaiah’s sign out of context. Perhaps because when I was younger and less experienced in scholarship, I did not bother to check the two passages, taking both of them at face value.
My experiences as civil engineer taught me a valuable lesson in science. Example, test and re-test, alway double-check, triple-check, and if you have check some more. And when I began my website (Timeless Myths), I have to check my sources.
And that’s what I did in 2000, check the source of the Gospel’s Immanuel, and re-read the entire chapter 7 of Isaiah.
Re-reading both passages together, just made think more clearly, coming to realisation that the Bible isn’t perfect. And the gospels quoted other passages from OT, that I found more Christian interpretations that don’t match with original contexts of OT scriptures.
That was the start of questioning the Bible, and the start of my road to agnosticism. And my agnosticism had nothing to do with science or history, not back then.
I only began questioning Genesis creation several years later, when I joined my first forum (Free2Code) in 2003, when I read for the first time, the debate between creationism and evolution.
I was absolutely clueless about Evolution, because my biology education stopped at Year 9 in high school, because the following years I chose to maths, chemistry and physics, and after high school, i did civil engineering course, which doesn’t require biology.
And though I had believe in Genesis creation, I was also clueless about “creationism”, and the people who called themselves “creationists”.
So I began to research on both subjects, Evolution and Creationism. Only then, that I finally looked at science, history and archaeology and compare it against the Genesis narrative.
Despite that I find the creation and flood of Genesis to be myths, they are still my favourite parts out of the whole Bible. My disagreement isn’t with the narratives themselves, but with creationists attempting to turn Genesis into science.