Antichrist (ἀντίχριστος
The Apostle John writes about the antichrist (ἀντίχριστος) in his first and second letters to the Church. The term "antichrist" is derived from a combination of a preposition (ἀντί) indicating opposition and the title "Christ" (Χριστός); therefore, it refers to one who is against Christ
We are first introduced to the concept of the antichrist in 1 John 2:18, where John writes about how we know it is the last hour. My little children, it is the last hour, and just as you heard that an antichrist is coming, now also many antichrists have come, by which we experientially know it is the last hour. The antichrist is the liar who denies that Jesus is the Messiah, 1 John 2:22. Who is the liar, except the one denying that Jesus is the Messiah? This one is the antichrist, the one denying the Father and the Son. Although these antichrists may claim to be from the Father, the ones that oppose Christ also reject the Father, 1 John 2:23. Everyone who denies the Son does not have the Father, the one verbally agreeing, has the Son and the Father. Every spirit that does not verbally agree that Jesus has come in the flesh is the antichrist, 1 John 4:3. and every spirit which does not confess (verbally agree) the Jesus is not out from God, and this is the [spirit] of the antichrist, which you have heard that is coming and now already is in the world. They are the deceivers who have gone out into the world, some even out from the assemblies, from the beginning of the Church, denying that Jesus has come in the flesh, 2 John 7. The antichrist is one who causes others to wander away from the truth. Because many deceivers have gone out into the world, the ones not confessing Jesus Christ has come in flesh. This is the deceiver (wanderer) and antichrist. In these latter times, many depart from the faith, giving heed to deceiving spirits and the teachings of demons, hypocrites who have seared their conscience in rejection of the truth, 1 Timothy 4:1-3. Now the Spirit explicitly said that in [the] last times certain ones would depart from the faith giving heed to deceiving spirits and teachings of demons, in hypocrisy speaking lies, having seared their own conscience, forbidding marriage, to refrain from foods which the God has created for partaking after thanksgiving to the ones believing and fully experientially knowing the truth. Therefore, the antichrist describes anyone who speaks in opposition to Christ, denying Who He is.
When John speaks of the antichrist that we have heard is coming in 1 John 2:18, he is not referring to the man of lawlessness, also known as the first beast of Revelation who has seven heads and ten crowns. Let no one deceive you according to any means, because except the leaving comes first and [then] the man of lawlessness is revealed, the son of destruction, 2 Thessalonians 2:3. And I was standing upon the sand of the sea and behold out from the sea a rising beast having ten horns and seven heads and upon his horns ten diadems and upon his heads blasphemous names (names that are falsely attributing something to him), Revelation 13:1. 1 John was written in 90 A.D. from Ephesus, and Revelation was written in 96 A.D. from the island of Patmos. Therefore, if John were referring to the antichrist in the book of Revelation when writing about the beast, he would have used this term to tie him back to his first and second letters to the Church. However, the antichrist is not used outside John’s first two letters, and within the letters, John specifically describes who the antichrist is. When it comes to the man of lawlessness, using the term antichrist as a synonym does the saints a disservice. We, of the Church, will never know who the man of lawlessness is and should be thankful, for he will be malignantly evil incarnate. The snatching of the Church by Christ will happen before the man of lawlessness is revealed and the wrath of God is poured out upon the earth, 2 Thessalonians 2:3. This one will set himself up in the Jewish temple in Jerusalem, declaring himself to be a god, 2 Thessalonians 2:4. The one opposing and exalting over every thing called god or worshipped, so that he sits in the holy of holies of the God displaying himself that he is a god.
The antichrist is among us now. In fact, there are many antichrists who walk among us denying the death for sins and resurrection of Christ three days later, opposing His physical resurrection, contesting that He is the Jewish Messiah, disagreeing that He is God in the flesh. Therefore, the Church would do well to heed the advice of the Apostle John to let the truth abide in us while rejecting the heresy these false teachers try to sneak in, 1 John 2:24. Let that which you have heard from a beginning abide in you, If that which you heard from a beginning abides in you, also the Son and the Father abide in you.