The ECFs and apologists reveal the identity of the restrainer. History confirms it.
Tertullian (2nd-3rd Century)
ON THE RESURRECTION, CHAP. XXIV
For the mystery of iniquity doth already work; only he who now hinders must hinder, until he be taken out of the way." What obstacle is there but
the Roman state, the falling away of which, by being scattered into ten kingdoms, shall introduce
Antichrist upon (its own ruins)?
APOLOGY, CHAP. XXXII.
There is also another and a greater necessity for our offering prayer in behalf of the emperors, nay, for the complete stability of the empire, and for Roman interests in general. For we know that a mighty shock im (43) pending over the whole earth--in fact, the very end of all things threatening dreadful woes---is only retarded by the continued existence of
the Roman empire.
John Chrysostom (c. 347-407)
Homilies on Second Thessalonians
HOMILY IV. 2 THESSALONIANS ii. 6--9.
"Only there is one that restraineth now, until he be taken out of the way," that is, when
the Roman empire is taken out of the way...
Augustine of Hippo (345 - 430)
City of God, Book XX, Chapter 19
For what does he [Paul] mean by "For the mystery of iniquity doth already work: only he who now holdeth, let him hold until he be taken out of the way: and then shall the wicked be revealed?" [2 Thess 2] I frankly confess I do not know what he means. ... However, it is not absurd to believe that these words of the apostle, "Only he who now holdeth, let him hold until he be taken out of the way," refer to
the Roman empire, as if it were said, "Only he who now reigneth, let him reign until he be taken out of the way." "And then shall the wicked be revealed:" no one doubts that this means
Antichrist.
While not commenting directly upon the
2 Thessalonians 2 passage, Cyril of Jerusalem affirmed the historical consensus that antichrist would not appear until the Roman empire had disappeared:
Cyril of Jerusalem (c. 315-386)
Catechetical Lectures
LECTURE XV.
ON THE CLAUSE, AND SHALL COME IN GLORY TO JUDGE THE QUICK AND THE DEAD; OF WHOSE KINGDOM THERE SHALL BE NO END, DANIEL vii. 9--14.
12. But this aforesaid
Antichrist is to come when the times of
the Roman empire shall have been fulfilled...
The early church believed that the pagan imperial Roman empire, under which the church was then living, was the restrainer (i.e. the "letter" or "withholder") which would eventually be "taken out of the way", and which, until then, was forestalling the emergence of the antichrist apostate papal Roman empire, which Paul describes as "that man of sin", "the son of perdition", and "that Wicked".
In the related verses in
2 Thess. 2 Paul does not reveal the identity of the restrainer. If Paul had believed that the Holy Spirit was the restrainer, there would have been no reason for Paul not to explicitly identify Him. But Paul did have a reason. John Chrysostom reveals it:
"Because if he meant to say the Spirit, he would not have spoken obscurely, but plainly, that even now the grace of the Spirit, that is the gifts, withhold him...But because
he said this of the Roman empire, he naturally glanced at it, and speaks covertly and darkly. For he did not wish to bring upon himself superfluous enmities, and useless dangers. For if he had said that after a little while the Roman empire would be dissolved, they would immediately have even overwhelmed him, as a pestilent person, and all the faithful, as living and warring to this end."
Paul did not wish to jeopardize the Church by attracting the attention of the Roman authorities.
The Thessalonians did know whereof Paul was speaking. 2 Thessalonians 2:5,6.
History subsequently confirmed the validity of Paul's inspired prescience.
And the Reformers recognized and understood both Paul and history.
