Revelation 13:17

Revelation 13:16 He causeth all . . . to receive a mark. The mark of the beast is some stamp or sign, by which all its worshipers should be known. In ancient days slaves were sometimes branded, as cattle are in our own age. The brand or mark of the beast would be some indelible sign which would designate with certainty those who were subject to his authority. To receive a mark in their right hand, or in their foreheads. A mark in the hand is supposed by some to represent the practice, while a mark in the forehead indicates the profession of life. It is remarkable, however, that a mark on the forehead, the sign of the cross made with water, converts a person into a Roman Catholic, and without this mark none are regarded as heirs of salvation.