Regarding the composite beast of Revelation 13, and the mystic number in verse 18:

Rev. 13:18 This calls for wisdom: let anyone with understanding calculate the number of the beast, for it is the number of a person. Its number is six hundred sixty-six.[NRSV]

I have very little interest in numerology, of which the 666 question is but a small example. In the first century AD, numerology was more generally employed than it is now. But it was Jesus Himself who chose to include the 666 verse in Revelation.

Irenaeus (c. 130 - c. 202) bishop of Lyons, was the first of the church fathers to stress the mystic number 666. He expected a future division of Rome, and cautioned all to wait for that division before attempting to solve the riddle. He did suggest several names that might fit the number, among them Lateinos (The Latin-speaking man) in Greek numerology: L=30; A=1; T=300; E=5; I=10; N=50; 0=70; S=200; total 666.–Ireneaus, Against Heresies, book 5, chap. 30, sec. 2.[Froom, The Prophetic Faith of our Fathers, vol. 1 pp. 248, 249, Review and Herald Publishing Association, 1950].

Hippolytus (died c. 236) followed the interpretation of Irenaeus. –Froom, vol. 1 p. 277.

Various subsequent writers offered a number of other interpretations, including this one: STUR (Saturn), the hidden god of Babylon, in the Aramaic language: S=200; T=60; U=400; R=6; total 666;

Pope Innocent III (1198-1216) applied the 666 number to the prophet Mohammed, but without attempting to find the number in his name. –Froom, vol. 1 pp. 675, 676.

The 666 number was first discovered within the title Vicarius Filii Dei by the Protestant writer Helwig (c. 1572-1643). He also nominated a number of other Latin titles which had been applied to the pope: Ordinarius Ovilis Christi Pastor, Dux Cleri, and Dic Lux. All of these computed to 666, but he promoted Vicarius Filii Dei as providing the closest fit. While advancing this interpretation, he admitted that Vicarius Filii Dei was an expansion of the official papal title Vicarius Christi. –Froom vol. 2 pp. 606, 607.

The exact term Vicarius Filii Dei (Vicar or Substitute for the Son of God) first appeared in The Donation of Constantine, which is now admitted to be a forgery, produced probably between 850 and 900 AD.

It is true that the popes made frequent use of The Donation of Constantine for hundreds of years, and that its authenticity was not questioned even by the papal opponents. But the forger did his work carelessly. While claiming the document to have Constantine as its author (died 337), it quotes the Bible from the Vulgate translation of St. Jerome (c. 342-420) who wasn't born until after Constantine was dead. Eventually the forgery was unmasked, so that the fraud has now been recognized for 500 years.

Thus the title Vicarius Filii Dei has very dubious origins. The universal and official word from Roman Catholic scholars and administrators has been to deny the title. I believe it is winsome and tactically superior to accept their disclaimer.

The main reason for continued interest in Vicarius Filii Dei is that its letters do add up to the figure 666. However that is a small point, since the same can be done for many other names, including that of eLLen goVLD VVhIte. (L+L+V+L+D+V+V+I; 50+50+5+50+500+5+5+1=666)

The book of Revelation has a main point: the struggle between truth in the person of Jesus Christ, and falsehood, in the person of Satan. Surely Satan himself has since his fall always wished to be the Substitute for Christ, or Substitute for the Son of God. And to the extent that anyone, Protestant, Catholic, Buddhist or atheist, denies the true Christ in favor of a substitute, he lends support to Christ's opponent, the father of lies.

Thus theologically, the same problem exists should any human assume the (acknowledged) title of Vicarius Christi.

"It is important that in defending the doctrines which we consider fundamental articles of faith, we should never allow ourselves to employ arguments that are not wholly sound. These may avail to silence an opposer, but they do not honor the truth. We should present sound arguments, that will not only silence our opponents, but will bear the closest and most searching scrutiny..." –5T 707, 708 (1889); GW 297-300; CWE 39, 40.

And that's why Adventists in recent years have had much less to say about the title, Vicarius Filii Dei.

In John's time, the number 666 already had a long history. My principal source for the following is R. Allan Anderson's Unfolding the Revelation:

The Babylonians, who invented the zodiac, considered each of the twelve signs to rule over the twelve months of the year. They further divided each of the 12 houses into 3 rooms. 12 x 3 = 36.

Each of the 36 designated gods ruled over his own 10 degrees of the 360 zodiac and over his 10 days of the 360-day zodiacal year.

We pause now to do some serial addition:

1+2+3+4+5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21+22+23+

24+25+26+27+28+29+30+31+32+33+34+35+36=666

It was believed that no god would strike you if you were wearing his identifying amulet. It would thus behoove you to invoke the numbers of each of the gods. The number which encompasses them all is 666.

An amulet which contained all of these numbers would insure the favor of all the gods, anywhere, anytime.

But the ancients didn't stop with using magic numbers in serial order. Arranging these numbers in a magic square could greatly compound their power.