Individual identity is often created from what we are not.  And what we are not lies on the other side of an imaginary boundary.  These boundaries become tools of isolation, separation, and ostracization.  This is why Jesus reframed sin around the boundaries. He didn't focus on unclean people. He highlights unrighteous partitions.  These partitions create different classes of people (clean and unclean), and they set the stage for some of the greatest atrocities in all of history.