(3) For.--The word further enforces the appeal to their memory: "Ye know what commandments . . . for this (you will recollect) is what God wants;" "a commandment given through the Lord Jesus," being, of course, identical with "God's will."

Your sanctification.--In apposition to the word this. The mere conversion, justification, salvation of us are not the aim of God: He would have us holy. The general idea of sanctification passes however here, as the following clauses show, into the more limited sense of purification.

Fornication.--The word is often used in late Greek for any kind of impurity, as, e.g., 1Corinthians 5:1, of incest; but here it must be understood in its strict sense. To the Gentile mind, while the wickedness of adultery or incest was fully recognised, it was a novelty to be told that fornication was a "deadly sin;" hence the strange connection in which it stands in the Synodal letter to the Gentile churches (Acts 15:20; Acts 15:29; Acts 21:25). This consideration also makes it easier to understand how St. Paul can praise these Gentile Thessalonians so heartily, although they need earnest correction on this vital point. It is a true instance of the sacerdotal metriopathy (or, compassionate consideration) towards the ignorant and deceived. (See Hebrews 5:1-2.)

Verse 3. - For this is the will of God. The phrase, "the will of God," has two significations in Scripture: the one is the determination of God - his decree; the other is his desire, that in which he delights - a will, however, which may be frustrated by the perversity of his creatures. It is in this latter sense that the word is here employed. Even your sanctification; complete consecration; holiness taken in its most general so. use. Our holiness is the great design of Christ's death, and is the revealed will of God. Some (Olshausen, Lunemann) restrict the term to moral purity, and consider the next clause as its explanation (comp. Romans 12:1). That ye should abstain from fornication; a vice fearfully prevalent among the heathen, and which, indeed, they hardly regarded as wrong. Especially it was the great sin of Corinth, from which the apostle wrote, the patron goddess of which city was Venus.

4:1-8 To abide in the faith of the gospel is not enough, we must abound in the work of faith. The rule according to which all ought to walk and act, is the commandments given by the Lord Jesus Christ. Sanctification, in the renewal of their souls under the influences of the Holy Spirit, and attention to appointed duties, constituted the will of God respecting them. In aspiring after this renewal of the soul unto holiness, strict restraint must be put upon the appetites and senses of the body, and on the thoughts and inclinations of the will, which lead to wrong uses of them. The Lord calls none into his family to live unholy lives, but that they may be taught and enabled to walk before him in holiness. Some make light of the precepts of holiness, because they hear them from men; but they are God's commands, and to break them is to despise God.For this is the will of God, even your sanctification,.... Which is another reason to enforce the above exhortation. "Sanctification" is internal or external. Internal sanctification is the work of the Spirit of God, and is a principle of spiritual life in the soul, a divine and spiritual light in the understanding, a flexion of the will to the will of God, and a settlement of the affections on divine things, and is an implantation of every grace in the heart. External sanctification arises from this, and lies in holiness of life and conversation; and is what is chiefly designed, as appears both by what goes before, and follows after: and this is "the will of God"; the will of his purpose and decree; for in the same decree that he wills the salvation of any by Jesus Christ, he also wills their sanctification in heart and life, and here and hereafter: and this is his approving will, or what is well pleasing in his sight, being agreeable to his nature, and divine perfections, particularly his holiness, in which he is glorious; and it is his will of command, and what he requires in his law, which is holy, just, and good, and perfectly agrees with the sound doctrine of the Gospel, and the revelation of his will in both.

That ye should abstain from fornication: which is particularly mentioned, abstinence from it being a branch of external holiness; and because that this sin was common among the Gentiles, and not esteemed a sin by them; as also to observe to these Christians, that as simple fornication was not to be allowed of, much less other acts of uncleanness, as adultery, incest, sodomy, and the like, which were iniquities that greatly prevailed among the Heathens. The Syriac version renders it, "from all fornication"; on this subject the apostle enlarges in some following verses.