A.T. Robertson Commentary 1 Thessalonians 4:7

"For God called us not for uncleanness, but in sanctification." — 1 Thessalonians 4:7 (ASV)

Not for uncleanness, but in sanctification (επ ακαθαρσια αλλ' εν αγιασμω). Sharp contrast made still sharper by the two prepositions επ (on the basis of) and εν (in the sphere of). God has "called" us all for a decent sex life consonant with his aims and purposes. It was necessary for Paul to place this lofty ideal before the Thessalonian Christians living in a pagan world. It is equally important now.