Restrainer or Perpetrator?
Under many translations to which I have access, 2 Thess. 2:7 suggests a “restrainer” is holding back the “mystery of lawlessness,” as in restraining lawlessness.
Interestingly, the KJV and NLT allow a different interpretation. Their renditions suggest the mystery of lawlessness will continue until its originator is “taken out of the way” (KJV). The NLT further suggests the secret of the origins of “this lawlessness” will remain secret until the one who keeps it secretive “steps out of the way.”
Not the Holy Spirit
All the commentators I have read reject the Holy Spirit as the “restrainer.” Their conclusions are mostly on grounds that withdrawal of the Holy Spirit, ostensibly to allow lawlessness to reach its fulfillment as depicted in Revelation, would be exactly that; a self-withdrawal rather than the scripturally implied removal by a third party.
A More Likely Probability
One probability for Paul’s meaning is that of civil authority. Paul, himself, had been protected by agents of the Roman Empire, that is civil authority, due to his status as a Roman citizen. Thus, it seems that likely that the mystery of lawlessness, and “the man of lawlessness” will be restrained until civil authority completely breaks down, and is removed, perhaps by executive or judicial mandate, or removes itself from curtailing lawlessness, or simply grants lawlessness through inaction. In Paul’s era, the chief executive was the emperor. It was he who passively or actively condoned action against Christians. In our era, the chief executive in the United States is the president. It will be he who actively or passively condones the withdrawal of an even-handed application of the rule of law to all citizens.
A possibility is that civil authority will simply refuse to protect the godly in order to garner favor from the ungodly and lawless, and therefore acquiesce to their demands of lawlessness.
Scriptural “Lawlessness”
“Lawlessness,” however, is not merely the absence of civil restraint that permits unlawful activities. In the context of Scripture, “lawlessness” most often refers to opposition to God, his work, and his people.