1 John 4:3

and every spirit that does not confess Jesus is not from God; this is the spirit of the antichrist, of which you have heard that it is coming, and now it is already in the world.

1 John 2:18

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 2:22

Who is the liar but the one who denies that Jesus is the Christ? This is the antichrist, the one who denies the Father and the Son.

2 John 1:7

For many deceivers have gone out into the world, those who do not acknowledge Jesus Christ as coming in the flesh. This is the deceiver and the antichrist.

2 Thessalonians 2:3-8

Let no one in any way deceive you, for it will not come unless the apostasy comes first, and the man of lawlessness is revealed, the son of destruction,

Treasury of Scripture Knowledge

Summary

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.

General references

Bible References

And this

1 John 2:18
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.
2 Thessalonians 2:7
For the mystery of lawlessness is already at work; only he who now restrains will do so until he is taken out of the way.
2 John 1:7
For many deceivers have gone out into the world, those who do not acknowledge Jesus Christ as coming in the flesh. This is the deceiver and the antichrist.

General references

Deuteronomy 18:21
You may say in your heart, ‘How will we know the word which the Lord has not spoken?’
John 8:47
He who is of God hears the words of God; for this reason you do not hear them, because you are not of God.”