My concern with any interpretation (understanding) of the written word is it's faithfulness to the written word.My rationale for the above ...
I can corroborate the written word (i.e. I can know that this is what was written by the apostles). Unfortunately, I cannot corroborate any similar basis for purely orally propogated tradition which may or may not hearken back to the time and tradition of the apostles.
I can appreciate your position. Your security in what is authentic Christianity rests on a methodology you have created for yourself. Otherwise, you would have to have faith.