NET
7 For the hidden power of lawlessness is already at work. However, the one who holds him back will do so until he is taken out of the way,
Darby
7 For the mystery of lawlessness already works; only [there is] he who restrains now until he be gone,
KJV
7 For the mystery of iniquity doth already work: only he who now letteth [will let], until he be taken out of the way.