Theodoret of Cyrus: Triumph of Gospel over Superstition

The mystery of iniquity is in fact already at work (v.7). Some commentators claimed that to Nero is given the name mystery of iniquity, and that he had become a worker of godlessness. It is my view, on the contrary, that the apostle is indicating the heresies that had sprung up: by leading many from the truth through them, the devil causes in advance the ruin of deceit. These people he referred to as mystery of iniquity for keeping the snares of iniquity hidden; the devil openly draws people away from God. Hence the apostle referred to his coming as revelation: he will then openly and plainly proclaim what he has constantly been working at in secret. Only until the one who is restraining it is taken away: the deception of superstition must be brought to an end, and the Gospel be preached.

- Theodoret of Cyrus (around A.D. 393 to around A.D. 457), Commentary on the Second Letter to the Thessalonians, Chapter 2, in Theodoret of Cyrus, Commentary on the Letters of St. Paul, Volume 2, p. 129 (2001), Robert C. Hill translator.