NET

3 For this is God’s will: that you become holy, that you keep away from sexual immorality,

Darby

3 For this is [the] will^D8799 of God, [even] your sanctification,^D8800 that ye should abstain from fornication;

Darby Bible Notes

will - The article is not before 'will' in Greek, and the force is much increased thereby. It is not merely the fact that God wills so, but it is a matter of God's will. God is looked at as a person in authority (not merely a divine Being), but the will is looked at characteristically, not merely as a fact that he so wills. This is of such a character that God himself wills it. sanctification, - Hagiasmos. See Note at Rom. 1.4.

KJV

3 For this is the will of God, [even] your sanctification, that ye should abstain from fornication: