You cannot hide a mark (or brand) located on the forehead; it is obvious for all to see. Further, as with Revelation 13:16, a mark on the forehead is meant to indicate that the recipient’s mind has been changed so that his manner of thinking on the issues of life is rooted in the person and work of the Lamb and the person and work of his Father. Despite all the pressures that come from living in a world filled with the dragon’s rage (allied as he is with two evil beasts), these elect root their thoughts (and thus worldview, complete with resulting words and deeds) in the gospel of Jesus Christ.
1 Then I looked, and behold, on Mount Zion stood the Lamb, and with him 144,000 who had his name and his Father’s name written on their foreheads.