Regarding Thomas Jefferson's approach to the new testament, this article asks the question, "Can you imagine the reaction if word got out that a president of the United States cut out Bible passages with scissors, glued them onto paper and said, 'I only believe these parts?"
Of course I can, because that is exactly what every person who "believes" the bible must do, mentally if not physically. It is necessary to cherry pick the parts a given person likes and leave out the rest. For example, Leviticus says homosexuality is an abomination (18:22), but it also says eating shellfish is an abomination(11:10) and I love that stuff. In my case, I simply discount all of it, which I find more intellectually honest than saying, "This passage is the immutable word of god, but this part doesn't matter."