The Bible has indeed been RECEIVED ais "Authoritative" ... This is so not least because an entire Community has received It so ...
teilhard
And thus we return to the topic. Absolute Moral Authority is whatever an entire community has accepted as morally authoritative. Different communities will of course differ on the source of that moral authority, it may be God, it may be some version of the Bible, or more commonly some quote mines from a particular version of the Bible, it may be the mediator for God, it may be Mrs. Grundy. In an advanced larger society the source is more diffuse, but no less definite. As an example in the large society of research scientists, one must not knowingly falsify data, one must cite all relevant influences on the research, and peer review either of knowledgeable people within a organization if it is proprietary research, or public if it is academic research. Any breech of these moral standards will result in "excommunication" and no scientific employment will be available.