Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition; Except there come a falling away first - We have the original word αποστασια in our word apostasy; and by this term we understand a dereliction of the essential principles of religious truth - either a total abandonment of Christianity itself, or such a corruption of its doctrines as renders the whole system completely inefficient to salvation. But what this apostasy means is a question which has not yet, and perhaps never will be, answered to general satisfaction. At present I shall content myself with making a few literal remarks on this obscure prophecy, and afterwards give the opinions of learned men on its principal parts.
That man of sin - Ὁ ανθρωπος της ἁμαρτιας· The same as the Hebrew expresses by איש און ish aven, and איש בליעל ish beliyaal; the perverse, obstinate, and iniquitous man. It is worthy of remark that, among the rabbins, Samael, or the devil, is called איש בליעל ואיש און ish beliyaal veish aven, the man of Belial, and the man of iniquity; and that these titles are given to Adam after his fall.
The son of perdition - Ὁ υἱος της απωλειας· The son of destruction; the same epithet that is given to Judas Iscariot, John 17:12 (note). The son of perdition, and the man of sin, or, as some excellent MSS. and versions, with several of the fathers, read, ανθρωπος της ανομιας, the lawless man, see 2 Thessalonians 2:8, must mean the same person or thing. It is also remarkable that the wicked Jews are styled by Isaiah, Isaiah 1:4, בנים משחיתים benim mashchithim, "children of perdition;" persons who destroy themselves and destroy others.