Verse 1-4 — If errors arise among Christians, we should set them right; and good men will be careful to suppress errors which rise from mistaking their words and actions. We have a cunning adversary, who watches to do mischief, and will promote errors, even by the words of Scripture. Whatever uncertainty we are in, or whatever mistakes may arise about the time of Christ's coming, that coming itself is certain. This has been the faith and hope of all Christians, in all ages of the church; it was the faith and hope of the Old Testament saints. All believers shall be gathered together to Christ, to be with him, and to be happy in his presence for ever. We should firmly believe the second coming of Christ; but there was danger lest the Thessalonians, being mistaken as to the time, should question the truth or certainty of the thing itself. False doctrines are like the winds that toss the water to and fro; and they unsettle the minds of men, which are as unstable as water. It is enough for us to know that our Lord will come, and will gather all his saints unto him. A reason why they should not expect the coming of Christ, as at hand, is given. There would be a general falling away first, such as would occasion the rise of antichrist, that man of sin. There have been great disputes who or what is intended by this man of sin and son of perdition. The man of sin not only practises wickedness, but also promotes and commands sin and wickedness in others; and is the son of perdition, because he is devoted to certain destruction, and is the instrument to destroy many others, both in soul and body. As God was in the temple of old, and worshipped there, and is in and with his church now; so the antichrist here mentioned, is a usurper of God's authority in the Christian church, who claims Divine honours.
Verse 5-12 — Something hindered or withheld the man of sin. It is supposed to be the power of the Roman empire, which the apostle did not mention more plainly at that time. Corruption of doctrine and worship came in by degrees, and the usurping of power was gradual; thus the mystery of iniquity prevailed. Superstition and idolatry were advanced by pretended devotion, and bigotry and persecution were promoted by pretended zeal for God and his glory. This mystery of iniquity was even then begun; while the apostles were yet living, persons pretended zeal for Christ, but really opposed him. The fall or ruin of the antichristian state is declared. The pure word of God, with the Spirit of God, will discover this mystery of iniquity, and in due time it shall be destroyed by the brightness of Christ's coming. Signs and wonders, visions and miracles, are pretended; but they are false signs to support false doctrines; and lying wonders, or only pretended miracles, to cheat the people; and the diabolical deceits with which the antichristian state has been supported, are notorious. The persons are described, who are his willing subjects. Their sin is this; They did not love the truth, and therefore did not believe it; and they were pleased with false notions. God leaves them to themselves, then sin will follow of course, and spiritual judgments here, and eternal punishments hereafter. These prophecies have, in a great measure, come to pass, and confirm the truth of the Scriptures. This passage exactly agrees with the system of popery, as it prevails in the Romish church, and under the Romish popes. But though the son of perdition has been revealed, though he has opposed and exalted himself above all that is called God, or that is worshipped; and has spoken and acted as if he were a god upon earth, and has proclaimed his insolent pride, and supported his delusions, by lying miracles and all kinds of frauds; still the Lord has not yet fully destroyed him with the brightness of his coming; that and other prophecies remain to be fulfilled before the end shall come.
Verse 13-15 — When we hear of the apostacy of many, it is a great comfort and joy, that there is a remnant according to the election of grace, which does and shall persevere; especially we should rejoice, if we have reason to hope that we are of that number. The preservation of the saints, is because God loved them with an everlasting love, from the beginning of the world. The end and the means must not be separated. Faith and holiness must be joined together as well as holiness and happiness. The outward call of God is by the gospel; and this is rendered effectual by the inward working of the Spirit. The belief of the truth brings the sinner to rely on Christ, and so to love and obey him; it is sealed by the Holy Spirit upon his heart. We have no certain proof of any thing having been delivered by the apostles, more than what we find contained in the Holy Scriptures. Let us then stand fast in the doctrines taught by the apostles, and reject all additions, and vain traditions.
Verse 16,17 — We may and should direct our prayers, not only to God the Father, through our Lord Jesus Christ, but also to our Lord Jesus Christ himself. And we should pray in his name unto God, not only as his Father, but as our Father in and through him. The love of God in Christ Jesus, is the spring and fountain of all the good we have or hope for. There is good reason for strong consolations, because the saints have good hope through grace. The free grace and mercy of God are what they hope for, and what their hopes are founded on, and not any worth or merit of their own. The more pleasure we take in the word, and works, and ways of God, the more likely we shall be to persevere therein. But, if we are wavering in faith, and of a doubtful mind, halting and faltering in our duty, no wonder that we are strangers to the joys of religion.