Origins of 666
The idea of the Triple God/dess has existed well before the beginnings of Christianity. The Christian God also holds the Trinity of Father, Son and Holy Ghost/Spirit, mirroring a religious aspect that dates well into the beginnings of solidified Pantheons.
The Christian God is said to create the world in 6 days on the 7th he rests. On the six day is the creation of man.
"And God went on to say: ‘Let us make man in our image, according to our likeness, and let them have in subjection the fish of the sea and the flying creatures of the heavens and the domestic animals and all the earth and every moving animal that is moving upon the earth.’ And God proceeded to create the man in his image, in God’s image he created him; male and female he created them."-Genesis 1:26, 27."
So we can see how the number of man is 6, being created on the Sixth day.
The Devil/Satan is label through history as the God of Flesh or something very similar depending on who/where you hear it. The God of Flesh is therefore also the God of Man, not of Christian man but of everyother man. Because the Devil is a "God" his number holds the Trinity aspect... being the Trinity God of Man, and Man’s number being 6... the Devil’s number becomes 666!
In Numerology, the number 6 is one of the most harmonius of numbers. First a brief background must be explained. The number 1 is a male number, both because of its phallic symbol and embodiment of masculine attributes such as physical and mental activity, and creative power. The number 2 is a feminine number, the II symbolic of the vaginal passage, and embodying feministic properties; accepeting, yielding, warm. The number 3 is another male number. Rotating it on it’s side symbolizes the male reproductive testies and it is also 1 (male) + 2 (female) making it the number of Offspring.
Background infomation done, mathematically 6 is both 2 (Female) times 3 (Male) and 1 (Male) + 2 (Female) + 3 (Offspring), making it extremely balanced and hence symbolic of harmonious sexual union. The upward (male) and downward (female) triangels superimpose to form the 6-pointed star. It also very much mirroring a woman’s pregnant expanding womb. It is both a female number and 2 x 3 and therefore represents the nurturing side of womanhood—the stable, safe, warm, domestic aspect of motherhood.
Because it is portrayed as such a female number, celebrating the beauty of motherhood and sexuality, it was shunned by the original Church. It was greatly in their favor to layer 6 with negative connotations, thus diminishing the popular practice of numerology and marking mothers with 6 of some item for good luck. (i.e. 6 flowers or a necklace with 6 beads.)
From here, a propaganda was built around this number and it is said to be an evil omen or some other such nonsense. In any case, whether you believe it is evil or not... that is the origin of the Number of the Beast. Oddly enough, more people avoid the number 13 than 666. Multiple hotels remove room number 13 from every floor but room number 666 will remain. Curious...