Me : Practices are just how we do stuff. Some of those become principles either because they are universally useful (i.e. focus on user needs) or because we believe they are useful due to some connection to a value we hold or once held (e.g. rituals).
Me : Agile is a set of practice, some of which are universally useful principles, some of which are context specific i.e. agile practices aren't suited to everything ditto lean ditto six sigma ...
Me : It's not a question of belief, iterative techniques are powerful ways of exploring and refining an unknown space. Ask my grandfather's long passed family, the Nazis were very iterative in their creation of mass murder.
Me : Universally useful principles or even context specific patterns can be used by any collective to improve its "performance" regardless of its culture and hence its values. Unfortunately, even the most vile organisations can learn to be effective.