Capital punishment eliminates the criminal.  That is the Muslim way.  Criminality is defined by their theology and supersedes any man-made law.  Failure to acknowledge that is also subject to the death penalty. Not, like Christian theology, 'Old Testament' belief superseded by Christian thought but, active, current, mainstream Muslim theology today.   And Saudi Arabia has been funding madrassas throughout the world teaching just that Wahabi belief system.  There is a theological reason that so many of the 9/11 murderers were from Saudi Arabia; they were raised in that belief and were also rebelling against Saudi Arabian government for not following it.