1 John 4:3

and every spirit that does not confess Jesus [acknowledging that He has come in the flesh, but would deny any of the Son’s true nature] is not of God; this is the spirit of the antichrist, which you have heard is coming, and is now already in the world.

1 John 2:18

Children, it is the last hour [the end of this age]; and just as you heard that the antichrist is coming [the one who will oppose Christ and attempt to replace Him], even now many antichrists (false teachers) have appeared, which confirms our belief that it is the last hour.

1 John 2:22

Who is the liar but the one who denies that Jesus is the Christ (the Messiah, the Anointed)? This is the antichrist [the enemy and antagonist of Christ], the one who denies and consistently refuses to acknowledge the Father and the Son.

2 John 1:7

For many deceivers [heretics, posing as Christians] have gone out into the world, those who do not acknowledge and confess the coming of Jesus Christ in the flesh (bodily form). This [person, the kind who does this] is the deceiver and the antichrist [that is, the antagonist of Christ].

2 Thessalonians 2:3-8

Let no one in any way deceive or entrap you, for that day will not come unless the apostasy comes first [that is, the great rebellion, the abandonment of the faith by professed Christians], and the man of lawlessness is revealed, the son of destruction [the Antichrist, the one who is destined to be destroyed],

Treasury of Scripture Knowledge

Summary

1 John 4:3

And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world.

And this

1 John 2:18

2 Thessalonians 2:7

2 John 1:7

General references

Deuteronomy 18:21

John 8:47

Bible References

And this

For the mystery of lawlessness [rebellion against divine authority and the coming reign of lawlessness] is already at work; [but it is restrained] only until he who now restrains it is taken out of the way.

General references

If you say in your heart, ‘How will we know and recognize the word which the Lord has not spoken?’

Whoever is of God and belongs to Him hears [the truth of] God’s words; for this reason you do not hear them: because you are not of God and you are not in fellowship with Him.”