Paul never failed openly to denounce the unbelieving Judaists as the chief opponents of the Christian religion — at that time. He could do so, because the Judaists had no direct political power,3918 especially outside of Judaea. But Paul did hesitate openly to identify the Heathen Roman Empire as the (then-soon-future) great opponent of Christianity.3919 For that would then have invited direct and widespread persecution of Christians everywhere.
Second. This already-present "man of sin" would only begin to persecute the Thessalonian Christians in earnest after another equally well-known power had been removed — the factor of "fallen away" or apostate Judaism. It was apostate Judaism which "held back" the full unveiling of the "man of sin" in his first phases. For that "man of sin" would not be unveiled fully, until apostate Judaism was first "out of the way"; removed from the Jerusalem temple precincts;3914 and indeed thereafter threatened
with deprival of its status as a permitted religion alias a religio licita throughout the Roman Empire.
As Paul told the first-century Thessalonian Christians: "And now, you know what keeps on holding back" the unveiling of the man of sin and the son of perdition who will keep on going into the temple of God to be enthroned there. He "will be seated there, while claiming to be divine."3920 Indeed, there he will "be unveiled — at his time.
"For the mystery of lawlessness [of the man of sin] already keeps on working. Only, he who now keeps on holding back [the full unveiling of the man of sin — will keep on holding back], until he [who keeps on holding him back] be out of the midst [initially also of the Jerusalem temple]. And then shall the lawless one be unveiled."3921
It is submitted then, that (in the first instance) the real restraining or "withholding" factor holding back early Roman persecution of Christians — was the (stateprotected) status which Judaism then enjoyed throughout the Roman Empire until the A.D. 66-70 destruction of Jerusalem after a three-and-a-half years' long siege by the pagan Romans. That commenced just sixteen years after Paul was writing his Second Epistle to the Thessalonians. As long as Judaism was tolerated by the Romans, Christianity appeared to the Roman authorities to be little more than a new sect of Judaism itself.3922
Before 66.5 A.D., Christianity was therefore tolerated by the Romans.3923 Yet it was not then tolerated by the apostate or "fallen away" Judaistic leaders. They persecuted Christians whenever they could; and they would soon incite the A.D. 54f Pagan Roman Emperor Nero and his Judaistic wife Poppaea Sabina against the Christians in 64 A.D.3924
However, after the fall of Jerusalem in A.D. 70, when the Roman power destroyed that rebellious city — Judaism ceased to be 'in the midst' of Jerusalem.3925 Then Rome herself — in the person of her General the later Emperor Titus — actually went and sat in that temple of God in Jerusalem, and claimed to be divine (before destroying that temple).3926
However, even after that — Christianity nevertheless continued to expand quite independently of shattered Judaism. This caused the Roman power (quite correctly) to cease regarding Christianity merely as a Jewish sect. Henceforth, Pagan Rome would (correctly) regard Christianity as the ever-expanding nemesis which would challenge and ultimately destroy the very basis even of the mighty Pagan Roman Empire itself.
As soon as Pagan Rome realized this, it was obvious her Emperors would at least sometimes viciously persecute Christianity just because it is Christianity — and viciously persecute Christians just because they are Christians. For Pagan Rome would then rightly regard Christianity as a direct threat to the continuing existence of the Heathen Roman Empire itself.3923