Dear children, this is the last hour; and as you have heard that the antichrist is coming, even now many antichrists have come. This is how we know it is the last hour.
The paternal note in John’s voice continues as he tenderly shepherds his beloved children in the faith through the many trials they will face in this world.
John warned his beloved spiritual children that “the world with its lust is passing away” – admonishing them not to participate in the alienation of this world – and now gives them the sign by which they know it is the last hour: the sign being the many antichrists that have come into the world.
This is the last hour (ἐσχάτη ὥρα ἐστίν): The Biblical concept of time sees this present age (characterized by evil) being separated from the age to come (characterized by eternal glory) by “the day of the Lord” – a time characterized by turmoil and trial leading up to the judgment of all things.
There is no definite article, “the”, in this phrase, meaning that John is not simply saying that we have come to the last hour chronologically, but that the time is late.
The hour is late and time is hastening towards the day of the Lord:
2nd Peter 3:3-4 (CSB) Above all, be aware of this: Scoffers will come in the last days scoffing and following their own evil desires, 4 saying, “Where is his ‘coming’ that he promised? Ever since our ancestors fell asleep, all things continue as they have been since the beginning of creation.”
John’s gospel sees a progression of “hours” from where Jesus tells his mother that his hour had not yet come (John 2:4; cf. John 7:30; 8:20), to the dawning of an hour when the true worshipers will worship the Father in Spirit and in truth (John 4:23), to the hour when the Son of Man must be glorified (John 12:23), and to Christ’s prediction of the hour of judgment coming upon the whole world (John 5:25-29). Many hours have passed and the time is drawing late.
Historic Perspective of Jerome (c. 347 – 420): Why is the lamb offered up in the evening and not during the day? The reason is plain enough, for our Lord and Savior suffered his passion at the close of the ages, which is why John called it the last hour.
The antichrist is coming: This refers to the sign given for the Church to look for:
2nd Thessalonians 2:3 (CSB) Don’t let anyone deceive you in any way. For that day will not come unless the apostasy comes first and the man of lawlessness is revealed, the man doomed to destruction.
The Antichrist is a figure empowered by Satan who functions as the eschatological enemy of Jesus Christ and the Church. In the context of apocalyptic literature, he performs false miracles, deceives many in order to discourage people from worshiping the true God, and fiercely persecutes God’s people.
Even now many antichrists have come: The Church must not only look out for the eschatological Antichrist, but also be on the alert for the many antichrists who have come into this world, performing false miracles, deceiving the Church, and persecuting God’s people.
Matthew 24:11, 24-27 (CSB) Many false prophets will rise up and deceive many. For false messiahs and false prophets will arise and perform great signs and wonders to lead astray, if possible, even the elect. 25 Take note: I have told you in advance. 26 So if they tell you, ‘See, he’s in the wilderness!’ don’t go out; or, ‘See, he’s in the storerooms!’ do not believe it. 27 For as the lightning comes from the east and flashes as far as the west, so will be the coming of the Son of Man.
Biblical Reasons 