Whether it happened or not was never the focus except for
  critics. What was always important was that it was used as an
  extreme example of obedience - an unthinkable scenario. It's
  even more vivid in the case of Job. If you go through the
  teaching and theological texts through the history of the
  religions, this story was always used as an example with which
  to debate and discuss and compare to one's own life. Could you
  do it? Would you do it? Whether it happened or not wasn't
  questioned because it didn't matter. What mattered was the
  lesson it gives. A thought experiment. Then again, I find nearly
  all thought experiments ridiculous beyond a certain point: How
  many people use examples from movies (like the Matrix) to base
  their real lives on? But that's my bias.