Catholic commentators have taught that the Antichrist is a man at the end times for many centuries. With the different senses of Scripture that the Catholic Church has always analyzed Scripture with, the Antichrist can be understood in various ways, but he is literally a man who is to come. Here are some footnotes that I have gathered for 2 Thessalonians for the Aquinas Study Bible, you will notice that these are quotes from the Church Fathers that go all the way back to the 2nd century.
2:3 the rebellion comes first: The Great Tribulation at the end of time. It will be a time when almost all men shall rush from the Truth to that Deceiver. (Ishodad of Merv) man of lawlessness: he is the Antichrist; as it is taught to us in both the ancient and the new prophecies, and especially by the Apostle John 1Jn 4:1-3. (Tertullian)
2:4 exalts himself against every: From this it shows that the Antichrist will even overturn idolatry, which the Devil introduced, and he will put an end to every sect which opposes him. (Theodore of Mopsuestia) temple of God: There are a few different interpretations. One is that he means, the Temple of the Jews which has been destroyed. For if the Antichrist comes to the Jews as Christ, and desires to be worshipped by the Jews, he will make great account of the Temple, that he may more completely beguile them; making it supposed that he is the man of the race of David, who shall build up the Temple which was erected by Solomon. (St. Cyril of Jerusalem) For he will not come to us Christians, but to the Jews- not for the sake of Christ and Christians, for which reason he is called Antichrist. (St. John of Damascus) Thus it appears that he will either be of the circumcision or at least circumcised himself, so that the Jews will have the confidence to believe in him. (Ambrosiaster) As for the second interpretation, it will be in the real divine temple, that is in the Catholic Church. (St. Andrew of Caesarea) Or he referred to the churches, in which he will arrogate to himself pride of place, striving to declare himself God. (Theodoret of Cyrus) St. John Chrysostom and Theophylact also include both the Jewish Temple and the Christian Churches. Theodore of Mopsuestia, Theodoret of Cyrus and Oecumenius include only the Christian Churches and not the Temple of Jerusalem. St. Irenaeus, St. Hippolytus, St. Cyril of Jerusalem, Ambrosiaster, St. John of Damascus, Apollinarius of Laodicea and Origen include only the Temple of Solomon. St. Andrew and Haimo give an either/or, as well as St. Augustine and Thietland. St. Augustine, Thietland and Lyra propose that the text may mean that the Antichrist becomes the counterfit temple in comparison to Christ as the Temple.
2:6-7 restraining: Severian says it’s the Holy Spirit that restrains, while Ishodad of Merv, Theodore of Mopsuestia, Theodoret of Cyrus say its God’s decree. St. John Chrysostom, Haimo, Ambrosiaster, Thietland, Tertullian claim its the reign of the Roman Empire. I am of the opinion that this is concerning the binding of the Devil that we read about in Revelation 20. The Fathers don’t appear to make that connection, but it seems quite obvious from the eyes of an ammillenialist. I assume that there are some reasons why the Fathers did not make that connection; 1) is because some Fathers had not considered the book of Revelation to be canonical, and therefore would not have connected those passages together. 2) St. Augustine is the one who brought greatest development early on to Rev. 20 and the binding of the Devil, and therefore had not advanced far enough with it to connect these two passages.** mystery of iniquity:** Some commentators claimed that to Nero is given the name mystery of iniquity, and that he had become a worker of godlessness. On the contrary, the apostle is indicating the heresies that had sprung up, by leading people away from God. (Theodoret of Cyrus) Or, the mystery of iniquity began with Nero, who in his zeal for idolatry killed the apostles at the instigation of his father the Devil, and went on to Diocletian, and most recently Julian. (Ambrosiaster) And that, all the wicked who have gone before are signs of the Antichrist. (St. Thomas Aquinas)
**2:9 activity of Satan: **Here Paul shows that the Antichrist is one thing, and Satan, who works in him, is another. (Ishodad of Merv) And this implies that Satan will use him as an instrument, working in his own person through the Antichrist. (St. Cyril of Jerusalem) The Antichrist will do everything with the Devil. (Interlinear Gloss)