Christian thoughts on the Anti-Christ?

The antichrist is only mentioned 4 times in the bible, and all 4 times occur in 1 John and 2 John. The antichrist is described to be simply one that does not believe in Christ. 1 John 2:18-19 even mentions multiple antichrists that are already here. I hear many Christians speak of the antichrist as one singular influential figure that will deceive the world and oppose Christianity in the end times. Some of these Christians are quick to accuse any popular political figure that they don't support as "THE antichrist." If the Bible describes the antichrist as one who doesn't accept Christ, and it is clear that there are many antichrists in the world (and always have been), then are they confusing the term antichrist with the Beast mentioned in Revelation? And how could this "great deceiver" be Barack Obama since he has such a low approval rating?