The Bible is not a textbook. The Bible was written for normal people to be understood, believed, obeyed, and enjoyed. This does not mean that there is nothing complex in the Bible, that we do not need teachers to instruct us, that knowing the original languages in which the Bible was written is not important, or that there cannot be disagreements between true Christians on certain interpretations of Scripture.
Still, with the above said, the Bible is still not a textbook. And still, even again with the above mentioned truths, the Bible is a simple book that God has given to us to help lead us to Him. When we read the Bible we need to keep in mind that, yes, we need to think seriously about these great truths that are given to us, and yet remember that the Bible is not a textbook. It is a practical book that God has given to us for all to understand.