There is only one reference in the Bible to the number 666. Where in the Bible? It is in a passage that is also associated with the Mark of the Beast. It is found in Revelation 13:15-18. It says,
“He [the second beast of Revelation 13] was granted power to give breath to the image of the beast [the first beast of Revelation 13], that the image of the beast should both speak and cause as many as would not worship the image of the beast to be killed. He causes all, both small and great, rich and poor, free and slave, to receive a mark on their right hand or on their foreheads, and that no one may buy or sell except one who has the mark or the name of the beast, or the number of his name. Here is wisdom. Let him who has understanding calculate the number of the beast, for it is the number of a man: His number is 666. ”
There are more references to the Mark of the Beast in the book of Revelation. They are as follows:
Revelation 14:9-13:
“Then a third angel followed them, saying with a loud voice, “If anyone worships the beast and his image, and receives his mark on his forehead or on his hand, he himself shall also drink of the wine of the wrath of God, which is poured out full strength into the cup of His indignation. He shall be tormented with fire and brimstone in the presence of the holy angels and in the presence of the Lamb. And the smoke of their torment ascends forever and ever; and they have no rest day or night, who worship the beast and his image, and whoever receives the mark of his name.” Here is the patience of the saints; here are those who keep the commandments of God and the faith of Jesus. Then I heard a voice from heaven saying to me, “Write: ‘Blessed are the dead who die in the Lord from now on.’ ” “Yes,” says the Spirit, “that they may rest from their labors, and their works follow them.”
Revelation 15:2-4 illuminates the Mark of the Beast further. Here John records,
“And I saw something like a sea of glass mingled with fire, and those who have the victory over the beast, over his image and over his mark and over the number of his name, standing on the sea of glass, having harps of God. They sing the song of Moses, the servant of God, and the song of the Lamb, saying: “Great and marvelous are Your works, Lord God Almighty! Just and true are Your ways, O King of the saints! Who shall not fear You, O Lord, and glorify Your name? For You alone are holy. For all nations shall come and worship before You, For Your judgments have been manifested.”
Revelation 16:1-2 record:
“Then I heard a loud voice from the temple saying to the seven angels, “Go and pour out the bowls of the wrath of God on the earth.” So the first went and poured out his bowl upon the earth, and a foul and loathsome sore came upon the men who had the mark of the beast and those who worshiped his image.”
Then in Revelation 19:20 it says
“Then the beast was captured, and with him the false prophet who worked signs in his presence, by which he deceived those who received the mark of the beast and those who worshiped his image. These two were cast alive into the lake of fire burning with brimstone.”
Finally in Revelation 20:4 John the Revelator gives us this description,
“And I saw thrones, and they sat on them, and judgment was committed to them. Then I saw the souls of those who had been beheaded for their witness to Jesus and for the word of God, who had not worshiped the beast or his image, and had not received his mark on their foreheads or on their hands. And they lived and reigned with Christ for a thousand years.”
Where in the Bible is 666 Mark of the Beast? All references can be found in the book of Revelation, starting from Revelation 13.
