1 tn Grk “the mystery of lawlessness.” In Paul “mystery” often means “revealed truth, something formerly hidden but now made widely known,” but that does not make sense with the verb of this clause (“to be at work, to be active”).
2 tn Grk “the one who restrains.” This gives a puzzling contrast to the impersonal phrase in v. 6 (“the thing that restrains”). The restraint can be spoken of as a force or as a person. Some have taken this to mean the Roman Empire in particular or human government in general, since these are forces that can also be seen embodied in a person, the emperor or governing head. But apocalyptic texts like Revelation and Daniel portray human government of the end times as under Satanic control, not holding back his influence. Also the power to hold back Satanic forces can only come from God. So others understand this restraint to be some force from God: the preaching of the gospel or the working of the Holy Spirit through God’s people.
3 tc ‡ Several important witnesses of the Alexandrian and Western traditions, as well as many other witnesses, read ᾿Ιησοῦς (Ihsous, “Jesus”) after κύριος (kurios, “Lord”; so א A D* F G Lc P Ψ 0278 33 81 104 365 1241 2464 pc latt sy co). But there is sufficient evidence in the Alexandrian tradition for the shorter reading (B 1739 1881), supported by the Byzantine text as well as Irenaeus. Although it is possible that scribes overlooked ᾿Ιησοῦς if the two nomina sacra occurred together (kMsiMs), since “the Lord Jesus” is a frequent enough appellation, it looks to be a motivated reading. NA27 places ᾿Ιησοῦς in brackets, indicating some doubts as to its authenticity.