Firstly, you can fully understand bible because the one who know the truly meaning is the one who wrote it.
Second, our mind is limited. That's why we can't understand God's mind.
Third, YOU NEED TO LEARN BIBLE IN THE RIGHT WAY AND IN DEPTH. IF YOU JUST READ AND UNDERSTAND IT LITERALLY, THEN IT'S ALL NONSENSE AND CONTRADICTION. PLEASE READ WITHIN THE CONTEXT, TIME AND PLACE, WHAT KIND OF WRITTEN WORK IS THAT. BIBLE WRITTEN BY VARIOUS PEOPLE IN VARIOUS AGE. LEARN BIBLE IN THE RIGHT WAY.
You cant understand the bible and you cant understand God but you believe in him and know he exists, this for me seems extremely contradictory. If you cant fully understand God or the Bible then what's the point? If the bible is really the word of God, then it should be clear to anyone, it should be easy to understand to everyone because that's the only thing the almighty God left humanity, a book. If I understand the book literally is garbage, you say. Why would God do that? To deceive us?
Now days no-one understands holy bible because the knowledge was lost or speculated or added in for crowd control purpourses... But still holy bilble can't be understood just by anywwho, the one who is humble reading it, and with respect, that one will understand... And with no speculations how is this how is that, no, it's like it's said in bible, the first time you are speculating from you mind oh so this is like this? That is not spirituality...
the final conclusion is this: Every holy text is readable, understandable, the trick is, to be humble, to love God and if you are so in this things, then God will provide the inteligence to understand him... But like he said, no-one understands God, even God himself doesn't understand himself, because when he trys to understand hiself, he's got allready bigger by the time when he want's to understand himself... He's infinite, allblisfull and eternal, and here we are, we, who can't even perceieve/understand what is infinite!
and if there is somebody that seeks the truth that was not yet tampered with human speculations, here is He: Bhagavad-Gita As It Is(it must be AS IT IS, if any other Gita it's a individual speculation, Bhagavad-Gita means Song of the Lord
And one more thing, I also didn't understand holy bible, until I read Bhagavad-Gita, in Bhagavad-Gita it's everything nice and tidy described: the manifestation of universe, how does this world works,basicly the instructions for how to live life the best way possible and then return back to Godhead some day... And if you read Bhagavad-Gita As It Is, I guarantee you that you will understand all holy scriptures plus you will know what it's not right in those holy scriptures... And Krishna won't give you the inteligence to understand Bhagavad-Gita, if you won't be reading it humble and with respect...