In "God's Word for Today" Steve Oliver writes:

Antichrist is a much-studied and much-debated topic. There are some schools of thought that see him as only symbolic of human rebellion against God, and others who view Antichrist as a movement or religion rather than a per-son. Among those who think he is an individual, some peo-ple speculate wildly in their search for this future world ruler. Six-six-six becomes the key to a secret code, which will enable them to identify him before he is revealed. Others equate his mark with some element of culture, such as VISA® credit cards or Monster Energy® drinks.
One of the effects of this search for Antichrist can be that we lose sight of the most important things about him — his evil and his futile rebellion against God. Rather than trying to figure out how quickly this prophesied individual will appear, we need to understand his character and guard against emulating that.

Discussion: How can we avoid "missing the forest for the trees" as we study Revelation (and even other scripture passages)?
Source: Christ, the Triumphant Lord: Adult Teacher's Insights, page 51.