The antichrist is the one who leads the belief system which goes against the teachings of Jesus Christ that are written in Scriptures.
39 Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me.
The antichrist, for example, is the one who does not believe that Jesus Christ can manifest Himself in the flesh. If you belong to that system that does not believe that Jesus Christ can become the Father in the last days, you are candidate to be under the rule of the antichrist.
2 John 1:7
7 For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist.