Gr. hagiasmos (see on Rom. 6:19), translated “sanctification” in 1 Thess. 4:3 (see comment there). The preposition (en) differs from that used with “uncleanness” (epi), and denotes the sphere in which God expects His called ones to live—the sphere of holiness (cf. Heb. 12:14). Holiness should characterize every aspect of the Christian’s life.

Gr. en, literally, “in.”

 See on ch. 2:12. The call of God is a powerful reason for eschewing all forms of impurity. Compare on 1 Cor. 6:18-20; 1 Peter 1:14-16.

 This preposition introduces the second reason given by Paul in his appeal for purity of conduct (see on v. 6).

 See on ch. 2:3. The preposition “unto” (epi) may be rendered “for,” since it refers to purpose. God has called no man to be unclean or impure.