Now, the question is: does the Bible contain only essential truths, or does it contain both essential and non-essential truths. Well, we first have to determine what truths would be classified essential. As I understand Christian beliefs, the only things that really matter are those things with eternal consequences. Thus, the most important truths would be those related to obtaining salvation. So, ask yourself this question. Is the knowledge of everything written in the Bible necessary for one to be saved? Obviously not. Else, I do not believe anybody would be saved.
Now, consider this. Does the Bible contain every truth necessary for salvation? If you think about it seriously, you'll see that it does not. After all, to be able to read and understand the essential truths of the Bible, one must have already come to understand the meanings of the words, in whatever language he or she is reading them in. They must understand how words are put together into sentences and how then to interpret correctly those sentences. They must already have a knowledge of how to discern the words of a charlatan from those of a sage. They must have an understanding of how the world works so as not to believe obvious falsehoods. Without all this precursor knowledge, it would be impossible to comprehend the essential truths of the Bible. Yes, a person lacking in some of these skills could get someone else to help him along, but then he would be latching onto a secondhand faith rather than one completely his own.
Oh, and don't forget that a person also needs skills in obtaining food and shelter in order to survive. A dead person is not really interested in truth, Biblical or not.