16 It also forced all people, great and small, rich and poor, free and slave, to receive a mark on their right hands or on their foreheads, 17 so that they could not buy or sell unless they had the mark, which is the name of the beast or the number of its name. 18 This calls for wisdom. Let the person who has insight calculate the number of the beast, for it is the number of a man.[1] That number is 666.

Matthew Henry's Commentary on Revelation 13:16-18

Commentary on Revelation 13:11-18

(Read Revelation 13:11-18)

Those who understand the first beast to denote a worldly power, take the second to be also a persecuting and assumed power, which acts under the disguise of religion, and of charity to the souls of men. It is a spiritual dominion, professing to be derived from Christ, and exercised at first in a gentle manner, but soon spake like the dragon. Its speech betrayed it; for it gives forth those false doctrines and cruel decrees, which show it to belong to the dragon, and not to the Lamb. It exercised all the power of the former beast. It pursues the same design, to draw men from worshipping the true God, and to subject the souls of men to the will and control of men. The second beast has carried on its designs, by methods whereby men should be deceived to worship the former beast, in the new shape, or likeness made for it. By lying wonders, pretended miracles. And by severe censures. Also by allowing none to enjoy natural or civil rights, who will not worship that beast which is the image of the pagan beast. It is made a qualification for buying and selling, as well as for places of profit and trust, that they oblige themselves to use all their interest, power, and endeavour, to forward the dominion of the beast, which is meant by receiving his mark. To make an image to the beast, whose deadly wound was healed, would be to give form and power to his worship, or to require obedience to his commands. To worship the image of the beast, implies being subject to those things which stamp the character of the picture, and render it the image of the beast. The number of the beast is given, so as to show the infinite wisdom of God, and to exercise the wisdom of men. The number is the number of a man, computed after the usual manner among men, and it is 666. What or who is intended by this, remains a mystery. To almost every religious dispute this number has yet been applied, and it may reasonably be doubted whether the meaning has yet been discovered. But he who has wisdom and understanding, will see that all the enemies of God are numbered and marked out for destruction; that the term of their power will soon expire, and that all nations shall submit to our King of righteousness and peace.