I've posed this same question to my die-hard pioneer MIL and cannot get her to give me an answer based on the bible. She will spout off the answer that comes from a magazine but when pressed to use JUST scriptures from the bible, it can't be done.
I asked her one time how we know that the Christian Greek scriptures are meant for the anointed only and she could not answer that one either, which goes along with Jesus not being the mediator for all mankind but just the anointed. I always found that one very hard to swallow.