Wouldn't believing in the fundamental truth of the words in the bible be enough?
That is such a loaded question. The Bible has to be the most edited book in the world. It has come to us in a form that was filtered through many languages and translations, has had many authors of suspect intention, and it primarily represents the limited awareness of people barely removed from caves.
Are we to embrace the old or new testament to discern this fundamental truth? If the fundamental truth you allude to is indeed so fundamental, wouldn't it also be natural? If natural, wouldn't it be self evident. And, if self evident, why all the Bible thumpers?
The only fundamental truth that occurs to me about the Bible is that it chronicles the penchant for psychosis in our species.