Encoding information in your hand and head has already happened. Your memory, and the ID card you hold in your hand. Sorry, if the Mark was to be refused, you missed the opportunity. Or maybe it speaks of a “spritual Mark”.
I think it is really a mark or brand, with a man’s name encoded somehow mathematically meaning 666(or 606...some quibble that the translation was wrong). Something visible that can be seen for crowd control purposes or quickly spotting who was or wasn’t from a mixed crowd of folks. This is not to say that some chip might not be involved as well