II Timothy 3:16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness.
This oft quoted scripture is the root of the understanding that every word of the Bible is applicable today. Several things are noteworthy in trying to understand this verse. One thing most would admit is that, when these words were written, the Bible, as we know it, had not yet been completed. Not every book of the current day Bible had been written and certainly the canonization process, which assembled all the books, had not occurred. Most logically the scriptures to which Paul referred were those of the OT. This verse in no way guarantees that what the canonization process of the 4th Century designated as the Bible is what Paul had in mind. One can assume so, but this verse adds no weight to that assumption.
The second point is the question of how the scriptures instruct. Do they teach as an example of what to believe and do, or do they serve as an illustration of what not to do? Most, who are familiar with the Bible, would likely admit that much in the Bible does not describe proper thought and conduct; so, having recognized that, every reader must differentiate between these different aspects of the truth- what to do and what not.
For example, when God commanded
Likewise, when the Moses enjoined the Israelites to completely annihilate those among them who taught of strange gods (Deuteronomy 13) is that our guidance today. Should this example guide a nation ostensibly committed to religious freedom? It's in the book and supposedly instructive in some sense, so what do I learn, having read this? If this directive was ethically and morally acceptable in the OT, why not today? Why is it in the Bible at all, if it is not a positive example of right conduct?
Issues like these are why mindless reference to isolated scriptures as unassailable proof of divine truth is so meaningless. Until someone decides what it means and implies, any scripture amounts to nothing more than words on a page. If a conclusion leads to a position which is ethically and logically unreasonable, then that objection cannot be summarily dismissed, especially by insisting that what the Bible says and means is crystal clear.