Since this mark only comes around after the 7th Trumpet starts to sound declaring time over for Adam's dead corruptible flesh, it is physical. As God stamps this expiration date of ultimate death on every human at the same time their names are removed from the Lamb's book of life.
Once a person is removed from the Lamb's book of life, God is no longer bound to redeem that person. They had to at the point of no return make a conscious decision to be removed.
Notice that Satan prohibited participating in his government and economy until they receive the mark. Satan is not handing out the mark, nor forcing it on anybody. I think people will face God directly while looking at the GWT and asked to be removed from the Lamb's book of life, and thus God stamps the expiration date of Adam's punishment as a physical reminder to whom they now belong to, Satan the father of all disobedience. What is wrong with the 144k walking around with God's seal on them?
At this point, all can see the face of the one sitting on the GWT: Revelation 6:14-16.
"And the heaven departed as a scroll when it is rolled together; and every mountain and island were moved out of their places. And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains; And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne."
When heaven is rolled back as in dissolved in 2 Peter 3, spiritual blindness will be gone as well. These humans are dead and dying anyway, looking on God's face at that time will not matter, like it has over the last, almost 6,000 years.
Still not sure why some cannot grasp the sudden and unexpected change that is soon to happen to this earth. Trying to force Revelation into the first century is about as wise as burying one's head in the sand.
People expect this man of sin to be revealed is like introducing the next presidential candidate. Satan is about to be free to come out of hiding. Do you think he had a lot of attention and grandstanding in the first century? Satan appeared to Jesus in the wilderness, so he was out stretching his legs then. But do you really think he was playing the part of the dragon then, which would just prove to them, that if he existed then God and Jesus would be legitimized and faith would be meaningless.
God cannot in good faith remove names from the Lamb's book of life until Jesus removes all the seals. The opening of the 7th Seal will allow names to be removed. That is why the Second Coming at the 6th Seal happens and the 144k are sealed by God. Salvation is no longer by faith. John points this fact out that when the 6th Seal is opened, all on earth will see God sitting on that GWT. They will see Jesus come to earth as the Lamb of God, the Messiah about to sit on His throne as King. All that these people can think about is, "O boy, we are in trouble, the wrath of the Lord is about to fall" The removal of the firmament revealing that Satan's 14 billion year old universe is just a virtual mind game. The sudden appearance of God on the GWT, and the Lamb will certainly bring Satan out of the shadows.
Yet many here present arguments that Revelation already happened and there is really nothing ahead that will change, any time soon. Others claim it will be over so quickly, that if any one blinked, they will not even experience anything that happened.