Many Christians have associated the number 666 with the anti-Christ, as foretold in the Book of Revelations. However, these people are forgetting the original historical context in which this biblical prophetic book was written. It was encouraging a beleaguered Christian community to stay true to their beliefs and not succumb to the pressures of the hostile world around them. Its vivid images and symbols were intended to be symbolic, not shapeable into whatever someone wants them to mean. The number 666 is just one of many such examples.
For example, the number is often associated with the beast because of a numerology technique called gematria, which assigns a numeric value to each letter of the alphabet. So adding up the values of the letters in a given word will "spell" that word with a particular number. The phrase in Revelations that mentions the beast's number refers to the fact that, through gematria, the letters in his name add up to 666. Various scholars have suggested that the "beast" in this context refers to Emperor Nero, though there is not sufficient evidence to support this claim.
In addition, the Islamic religion uses a letter-to-number system called Abjad to give numeric equivalences to names. Exactly how this system works is beyond the scope of this article and requires a knowledge of Arabic. It is, however, worth noting that the number 666 does have a significant connection to Islam and the Islamic calendar.