Antichrist (Greek: Ἀντίχριστος, translit. antichristos) is a term found five times in the New Testament, solely in the First and Second Epistle of John (once in plural form, and four times in the singular).
In the First Epistle of John appears the first mention of the word "antichrist", a term which the author then explains:
Children, it is the last hour, and as you have heard that antichrist is coming, so now many antichrists have come. Therefore we know that it is the last hour. They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us. But you you have been anointed by the Holy One, and you all have knowledge. I write to you, not because you do not know the truth, but because you know it, and because no lie is of the truth. Who is the liar but he who denies that Jesus is the Christ? This is the antichrist, he who denies the Father and the Son.
Before announcing the Great Tribulation, the Gospel of Matthew (chapter 24) alerts his disciples not to be deceived by the false prophets, which will claim themselves as being Christ, operating "great signs and wonders".
According to Church Father John Chrysostom, one such antichrist, commonly understood to rise in power in the last days and often associated with the "little horn" in Daniel's final vision and the "man of sin" in Paul the Apostle's Second Epistle to the Thessalonians,is explained by Paul as follows:
And then the lawless one will be revealed, whom the Lord Jesus will kill with the breath of his mouth and bring to nothing by the appearance of his coming. The coming of the lawless one is by the activity of Satan with all power and false signs and wonders, and with all wicked deception for those who are perishing, because they refused to love the truth and so be saved. Therefore God sends them a strong delusion, so that they may believe what is false, in order that all may be condemned who did not believe the truth but had pleasure in unrighteousness.
In Islamic eschatology, Al-Masih ad-Dajjal (المسيح الدجال) is an anti-messiah figure (similar to the Christian concept of an antichrist), who will appear to deceive humanity before the second coming of "Isa", as Jesus is known by Muslims.
The concept of an antichrist is absent in traditional Judaism, although in some medieval texts the symbolic figure Armilus appears.
