The mark may end up being one of these tattoos and the tattoos can be invisible.
This tattoo eerily mirrors Ezekiel 9:1-11, and counterfeits Christs action in the passage. The passage reads as follows:
Then He called out in my hearing with a loud voice, saying, “Let those who have charge over the city draw near, each with a deadly weapon in his hand.” 2 And suddenly six men came from the direction of the upper gate, which faces north, each with his battle-ax in his hand. One man among them was clothed with linen and had a writer’s inkhorn at his side. They went in and stood beside the bronze altar.
3 Now the glory of the God of Israel had gone up from the cherub, where it had been, to the threshold of the temple.[a] And He called to the man clothed with linen, who had the writer’s inkhorn at his side; 4 and the Lord said to him, “Go through the midst of the city, through the midst of Jerusalem, and put a mark on the foreheads of the men who sigh and cry over all the abominations that are done within it.”
5 To the others He said in my hearing, “Go after him through the city and kill; do not let your eye spare, nor have any pity. 6 Utterly slay old and young men, maidens and little children and women; but do not come near anyone on whom is the mark; and begin at My sanctuary.” So they began with the elders who were before the temple. 7 Then He said to them, “Defile the temple, and fill the courts with the slain. Go out!” And they went out and killed in the city. 8 So it was, that while they were killing them, I was left alone; and I fell on my face and cried out, and said, “Ah, Lord God! Will You destroy all the remnant of Israel in pouring out Your fury on Jerusalem?”
9 Then He said to me, “The iniquity of the house of Israel and Judah is exceedingly great, and the land is full of bloodshed, and the city full of perversity; for they say, ‘The Lord has forsaken the land, and the Lord does not see!’ 10 And as for Me also, My eye will neither spare, nor will I have pity, but I will recompense their deeds on their own head.”
11 Just then, the man clothed with linen, who had the inkhorn at his side, reported back and said, “I have done as You commanded me.”
During the middle of the Tribulation, the Antichrist is the one with the inkhorn, The man clothed in linen with the inkhorn in this passage is none other than Jesus Christ. During the middle of the Tribulation, the Antichrist is the one with the inkhorn, it is his counterpart to the spiritual version and those marked will be those who are his and the righteous who refuse the mark will be killed.