“Children, it is the last hour; and just as you heard that antichrist is coming, even now many antichrists have appeared; from this we know that it is the last hour.” (1 John 2:18) Key here is understanding what is meant by the “last hour.” We’ve already talked about this letter, was likely written around A.D. 85 and 90, so how can John claim that this is the last hour? The term that is translated as hour is actually hōra which the Word Study Dictionary defines as “… a definite space or division of time recurring at fixed intervals, as marked by natural or conventional limits. Figuratively, of a season of life…”
In verse 17 of this chapter we get a clue as it states the world is passing away. Isaiah 65:17, 2 Peter 3:13, Matthew 5:18, Revelation 21:1, and Matthew 24:35 all state that this world will pass away, but not before Christ’s return. This is the time period that is being referred to; it’s that period of time between Christ’s resurrection and coming return.
John’s warns us that in this “final hour” the enemy will ramp up his effort to deceive. “This lying spirit denies the reality of Christ’s first coming, and the wonderful truth that through the Holy Spirit, Jesus Christ can live His life in us—the very same life He lived when He was on earth—a life of obedience to the law of God! Therefore, an antichrist is one who is against Christ—against His law, and against His way of life. This spirit of antichrist or lawlessness, so common today, was already widespread in the Apostle Paul’s day.” (Reference)