Making Sense of the Most Disturbing Statement in the Bible

No statement by God seems more morally challenging than the prophet Samuel's demand for the complete annhilation of the Amalekites and their animals, followed by his condemnation of Saul for failing to kill King Agag and the choicest of the animals.  The Amalekites are equated with the nature of evil itself, and so the resurgence of evil and especially genocidal anti-Semitism throughout the rest of time is somehow linked to the failure to "complete the job" of vanquishing them earlier on.  In this very brief teaching, I try to learn a lesson we might otherwise resist from this troublesome piece of Tanakh:  the tendency to fail to complete the job, often through unacknowledged selfish interest that hides beneath the seemingly noble action of "moving on."