Who is “the man of sin?”

Let no man deceive you by any means: for that day shall not come, except there come a falling away (apostasia) first, and that man of sin be revealed, the son of perdition; Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.Remember ye not, that, when I was yet with you, I told you these things? (2 Thessalonians 2:3-5)

Latter-day Saints have long understood this passage to refer to refer to the apostasy of primitive Christianity. This raises the question, however, of who is this “son of perdition” or “man of sin?” I think we first have to define what “the temple” is in this context. I believe it is figurative for the church itself in the same way Paul uses it in Ephesians 2:19-22. God was thought to literally dwell in the temple and to figuratively dwell in the Church through the Holy Spirit (see Ephesians 2:19-22). Therefore, “the man of sin” is someone who takes the place of divine revelation in God’s church. Here is some insightful commentary from two protestant scholars:

By this apostasy we are not to understand a defection in the state, or from civil government, but in spiritual or religious matters, from sound doctrine, instituted worship and church government, and a holy life. The apostle speaks of some very great apostasy, not only of some converted Jews or Gentiles, but such as should be very general, though gradual, and should give occasion to the revelation of rise of antichrist, that man of sin. This, he says (2 Th. 2:5), he had told them of when he was with them, with design, no doubt, that they should not take offence nor be stumbled at it. And let us observe that no sooner was Christianity planted and rooted in the world than there began to be a defection in the Christian church. It was so in the Old Testament church; presently after any considerable advance made in religion there followed a defection: soon after the promise there was revolting; for example, soon after men began to call upon the name of the Lord all flesh corrupted their way, – soon after the covenant with Noah the Babel-builders bade defiance to heaven, – soon after the covenant with Abraham his seed degenerated in Egypt, – soon after the Israelites were planted in Canaan, when the first generation was worn off, they forsook God and served Baal, – soon after God’s covenant with David his seed revolted, and served other gods, – soon after the return out of captivity there was a general decay of piety, as appears by the story of Ezra and Nehemiah; and therefore it was no strange thing that after the planting of Christianity there should come a falling away (Matthew Henry [1662-1714].Commentary on the Whole Bible).

We have the original word apostasía 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 (Adam Clarke [1715-1832]. Commentary on the Bible).

James E. Talmage seems to agree with the Protestant commentary:

The Roman pontiff exercised secular as well as spiritual authority; and in the eleventh century arrogated to himself the title of Pope, signifying Father, in the sense of paternal ruler in all things. During the twelfth and thirteenth centuries the temporal authority of the pope was superior to that of kings and emperors; and the Roman church became the despotic potentate of nations, and an autocrat above all secular states. Yet this church, reeking with the stench of worldly ambition and lust of dominance, audaciously claimed to be the Church established by Him who affirmed: “My kingdom is not of this world.” The arrogant assumptions of the Church of Rome were not less extravagant in spiritual than in secular administration. In her loudly asserted control over the spiritual destinies of the souls of men, she blasphemously pretended to forgive or retain individual sins, and to inflict or remit penalties both on earth and beyond the grave. She sold permission to commit sin and bartered for gold charters of indulgent forgiveness for sins already done. Her pope, proclaiming himself the vicar of God, sat in state to judge as God Himself; and by such blasphemy fulfilled the prophecy of Paul following his warning in relation to the awful conditions antecedent to the second coming of the Christ: “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; Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.” (James E. Talmage. Jesus the Christ, 693.)