2 Thessalonians 2:7

For the mystery of lawlessness is already working, only he who restrains it until now will develop from the midst.

Revelation 17:5

and upon her forehead a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF WHORES AND OF THE ABOMINATIONS OF THE EARTH.

Revelation 17:7

And the agent said to me, Why did thou wonder? I will tell thee the mystery of the woman, and of the beast that carries her, which has the seven heads and the ten horns.

1 John 2:18

Children, it is the last hour. And as ye heard that the antichrist comes, and now many antichrists have developed, from which we know that it is the last hour.

1 John 4:3

and every spirit that does not confess Jesus Christ has come in flesh is not of God. And this is that of the antichrist, which ye have heard that it comes, and is now in the world already.

Acts 20:29

For I know this, that after my departure grievous wolves will enter in among you, not sparing the flock.

Colossians 2:18-23

Let no man umpire against you insisting on self-mortification, and worship of the heavenly agents, intruding in things that he has not seen, vainly puffed up by the mind of his flesh,

1 Timothy 3:16

And without controversy great is the mystery of piety. God was manifested in flesh, justified in spirit, seen by heavenly agents, proclaimed among nations, believed in the world, taken up in glory.

2 Timothy 2:17-18

and their word will have a feeding field like gangrene, of whom are Hymenaeus and Philetus,

Treasury of Scripture Knowledge

Summary

For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way.

Bible References

The mystery

1 Timothy 3:16
And without controversy great is the mystery of piety. God was manifested in flesh, justified in spirit, seen by heavenly agents, proclaimed among nations, believed in the world, taken up in glory.
Revelation 17:5
and upon her forehead a name written, MYSTERY, BABYLON THE GREAT, THE MOTHER OF WHORES AND OF THE ABOMINATIONS OF THE EARTH.

Doth

Acts 20:29
For I know this, that after my departure grievous wolves will enter in among you, not sparing the flock.
Colossians 2:18
Let no man umpire against you insisting on self-mortification, and worship of the heavenly agents, intruding in things that he has not seen, vainly puffed up by the mind of his flesh,
2 Timothy 2:17
and their word will have a feeding field like gangrene, of whom are Hymenaeus and Philetus,
1 John 2:18
Children, it is the last hour. And as ye heard that the antichrist comes, and now many antichrists have developed, from which we know that it is the last hour.
1 John 4:3
and every spirit that does not confess Jesus Christ has come in flesh is not of God. And this is that of the antichrist, which ye have heard that it comes, and is now in the world already.

He who

2 Thessalonians 2:6
And now ye know that which restrains, for him to be revealed in his own time.