Revelation 13:16-18

And he causeth all, both small and great, rich and poor, free and bond, to receive a mark in their right hand, or in their foreheads: And that no man might buy or sell, save he that had the mark, or the name of the beast, or the number of his name. Here is wisdom. Let him that hath understanding count the number of the beast: for it is the number of a man; and his number is Six hundred threescore and six.

Mark 13:14-20

But when ye shall see the abomination of desolation, spoken of by Daniel the prophet, standing where it ought not, (let him that readeth understand,) then let them that be in Judaea flee to the mountains: And let him that is on the housetop not go down into the house, neither enter therein, to take any thing out of his house: And let him that is in the field not turn back again for to take up his garment. But woe to them that are with child, and to them that give suck in those days! And pray ye that your flight be not in the winter. For in those days shall be affliction, such as was not from the beginning of the creation which God created unto this time, neither shall be. And except that the Lord had shortened those days, no flesh should be saved: but for the elect’s sake, whom he hath chosen, he hath shortened the days.

2 Thessalonians 2:1-4

Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto him, That ye be not soon shaken in mind, or be troubled, neither by spirit, nor by word, nor by letter as from us, as that the day of Christ is at hand. Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition; Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.