Now we have a new method, one that is a better fit than previous speculations.  This small observation falls in with other  speculations as well, but it seems the move toward a Mark of some sort, a Mark that all of society would eventually embracem would be something that is not really visible all the time.  It would make sense that people would not like going around with a tattoo or some other disfiguring mark, and many would reject such a thing, not for religious reasons but for cosmetic reasons.  The religious objections would be ever present.  But, what if the Satan influenced societies of the world were able to mark everyone with an invisible marker, something that would not require a tattoo or some piece of metal slipped under the skin -- not your phone and not a credit card (things that you could lose), but an invisible mark, easily applied, permanant and still detectable with the right equipment, something simple.  Our money already has this technology with hidden images only detectable under a black light.  This bioluminescence is a possible answer.  And how appropriate the name -- Luciferase, a marker many people in the religious community, at least those who bother to study their Bibles, are familiar.  Lucifer, the Light Bringer was a name used for that Old Serpent himself, Satan.