For this is the will of God, even your sanctification - It is the will or command of God that you should be holy. This does not refer to the purpose or decree of God, and does not mean that he intended to make them holy - but it means that it was his command that they should be holy. It was also true that it was agreeable to the divine will or purpose that they should be holy, and that he meant to use such an influence as to secure this; but this is not the truth taught here. This text, therefore, should not be brought as a proof that God intends to make his people holy, or that they are sanctified. It is a proof only that he requires holiness. The word here rendered “sanctification” - ἁγιασμὸς hagiasmos - is not used in the Greek classics, but is several times found in the New Testament. It is rendered holiness, Romans 6:19, Rom 6:22; 1 Thessalonians 4:7; 1 Timothy 2:15; Hebrews 12:14; and sanctification, 1 Corinthians 1:30; 1Th 4:3-4; 2 Thessalonians 2:13, and 1 Peter 1:2; see the Romans 6:19 note; 1 Corinthians 1:30 note. It means here “purity of life,” and particularly abstinence from those vices which debase and degrade the soul Sanctification consists in two things:
(1) In “ceasing to do evil;” and,
(2) In “learning to do well.” Or in other words, the first work of sanctification is in overcoming the propensities to evil in our nature, and checking and subduing the unholy habits which we had formed before we became Christians; the second part of the work consists in cultivating the positive principles of holiness in the soul.
That ye should abstain from fornication - A vice which was freely indulged among the pagan, and to which, from that fact, and from their own former habits, they were particularly exposed. On the fact that they were thus exposed, and on the reasons for these solemn commands on the subject, see the Acts 15:20 note, and 1 Corinthians 6:18 note.