What completely put me off the (according to fundamentalists) Biblical God (and I attended a Reformed Baptist Church, because Baptists, were not strict enough) was predestination.
God predestined certain people to be saved through Christ, before the foundation of the world. So only those who are predestined are saved - yet God damns those he himself did not predestine.
He's supposed to be a loving father, yet by all accounts the vast majority of his children will end up in hell/Hades as a stopping place before being flung into the eternal lake of fire after the final judgment.
There is nothing my child could do that would cause me to act that way - especially if I'd set him up to fail in the first place. I expect God to be a better parent than me.
In fact, the Bible is a hodge podge of writings by men (because the women's writings were not included), somewhat arbitrarily approved of at particular times.
For instance, OP, are you in favour of the Apocryphal books? They were part of the Bible (Septuagint) and were used by the early Christians. Catholics still consider them canonical - but protestants don't, and fundamentalists do tend to be Protestant.
M Scott Peck describes fundamentalists as less spiritually developed than atheists, and with good reason - a brief explanation here:
https://eriksholisticcornucopia.wordpress.com/2013/05/04/stages-of-faith-intro-to-m-scott-peck/