Would you believe me if I say no man knew entirely what the Holy Bible teach ? I have not found one and I am 62 years old, I have been studying the Bible myself and reading books by various authors, theologians, evangelists. Listening to sermons for years, I can only say that God is God, and He is unfathomable.
So what do we need to study the Holy Bible ? answer: we need the Holy Spirit. How do we know the Holy Spirit is in us ? The Holy Spirit is also beyond our human understanding but He reveals the truth to us as He wills.
The Bible tells that God reveals Himself and the truth to humble and seeking people. So when we humble ourselves God will reveal more to us.