The Greek word translated "antichrist" is ἀντίχριστος (antichristos), which can either be understood to mean "one opposed to Christ"; it can mean "one who claims to be Christ"; and as it is in this case, both. In John's Epistles, the antichrist denies the Gospel message that Jesus is the Christ, that He is the Son of God, and that Jesus has already come in the flesh. In that sense, he is opposed to the true Christ. His motive is clear; he wants Israel to believe he is their Messiah. The four verses which mention the antichrist are: 1 John 2:18, 22; 4:3; 2 John 1:7.
The antichrist, according to Daniel 9:27 and Matthew 24:3-15, presents himself as Israel's Christ, promising he will protect them from their enemies, according to a seven-year peace covenant. But something very dramatic changes him. We are told that he suffers a mortal head wound, and in the following verses, we are told that he is healed and empowered by Satan. It is then that he becomes known as "the beast," and it is then that he demands that he be worshipped as god (Rev. 13:1-10). Much like Judas Iscariot, who became known to Jesus as the "son of perdition" when he was indwelt by Satan (Jn. 13:27; 17:12), the antichrist appears to become the "son of perdition" when he also experiences a similar indwelling (2 Thes. 2:3; Rev. 13:4).
The identity of the actual man known as the antichrist or the beast of Revelation, is unknown, and will only be revealed when he commits the "abomination of desolation" (Dan. 9:27; 11:31; 12:11; Mt. 24:15; Rev. 13:6). But I have a question for you. Are you an antichrist? John wrote that "even now are there many antichrists" (1 Jn. 2:18); and they "denieth that Jesus is the Christ" (1 Jn. 2:22)!
Christ is the Son of God; Christ died and rose again; Christ will return soon as King of kings and Lord of lords: are you longing for Him to come, or are you dreading that day? You are either a Christian, or you are an antichrist!