"This calls for wisdom. If anyone has insight, let him calculate the number of the beast, for it is man's number. His number is 666."
Since the second century, people have proposed all kinds of theories for a name that would whose letters would spell 666, from Nero Caesar to Hitler.
Revelation 13:18 calls for wisdom and insight to calculate the number of the beast: 666. All of the speculation that it adds up to a name misses the point. The Revelation never uses numbers to stand for letters. It always uses numbers as symbols for other things. For example, we have seen that 3 stands for God, 4 stands for the earth, 7 is perfection, and 12 stands for God’s people. Revelation often uses an imperfect number 3 ½, because it is half of 7. In Revelation 13:18, we have another imperfect number: 6. The number 6 is imperfect because it falls one short of 7, the perfect number. Notice that 666 is called a “man’s number,” not God’s number. And remember that the number 3 stands for God, because of the Trinity. So 777 would stand for Godly perfection. Thus the simplest explanation is that 666 stands for ungodly evil imitation of God. It could mean a specific future false prophet or Antichrist, but it can apply to anybody who puts himself and his ideas ahead of Jesus Christ. After all, since Satan does not know when Jesus will come back, he must always have antichrists and false prophets in waiting.