As culture makes something unacceptable as a belief, the belief is slowly eroded and the line is pushed further towards one side or another, pretty much the same phenomenon that we observe in politics and political systems. The consequence of this dichotomy is devastating, much more so than both beliefs held separately. On the one hand, absolutism gives any moral system the authority of tradition, inflexibility and pseudo-righteousness. On the other hand, the mental sloth of culture-based morality orients this inflexibility towards emotional compromise and evil. Of course, how religious people explicitly justify it is another matter.
Interpretation is tricky business.
We make mistakes in interpretation all the time, if only in common things like people's movements or speech. Well, not powerful enough to translate his words to english, anyway. It proves nothing about the source's intentions and feelings, but it shows a lot about the interpreter's own intentions and feelings, as we have seen. One can dissect and discuss interpretations of a work of fiction because it is art, and usually has a deeper meaning or deeper implications. When christians start to interpret the bible, they admit that it is a work of fiction.