The Lord God had instructed fathers in Israel to teach their children his precepts and added, You shall bind them as a sign on your hand, and they shall be as frontlets between your eyes
(Deuteronomy 6:8; see also Exodus 13:9, Exodus 13:16). The instruction was not meant to be literal but was intended as a way of saying that everything you did and thought was to be determined by and in submission to God’s instruction. (As it was, the Pharisees took the instruction literally and wore an amulet (or phylactery) on their foreheads when they prayed; Matthew 23:5.) The beast would copy God’s instruction with his own mark. By their conduct and their way of thinking these people would show that they were aligned with the beast and worshipped it.
16 Also it causes all, both small and great, both rich and poor, both free and slave, to be marked on the right hand or the forehead,