1 Thessalonians 4:3
For this is the will of God, [even] your sanctification, that ye should abstain from fornication:
Note 5 at 1Th 4:3: People are always wanting to know what God's will is for their lives. Usually, they are looking for specific direction about their careers, their marriages, or like things. Until they do God's general will revealed for all in Scripture, there is no reason to expect specific direction.
This verse gives us God's will for each one of our lives, and this should keep us busy until we die. As we become faithful in walking out God's general will for our lives, which is revealed in Scripture, then the Lord will give us more specific direction.
Note 6 at 1Th 4:3: The word "sanctification" means "separation to God...the separation of the believer from evil things and ways" (Vine's Expository Dictionary). There are two types of sanctification in the Christian life.
First, our born-again spirits (see note 2 at Joh 3:3) are instantly sanctified the moment we make Jesus our Lord (see note 17 at Eph 4:24). They remain this way regardless of fluctuations in our actions (Heb 10:10). Therefore, the sanctification that has already taken place in our spirits is a constant that forms the basis for our relationship with the Lord.
Second, it is not enough to only be separated unto God in our spirits. What has taken place in our spirits must manifest itself in our actions. This outward separation, or sanctification, is not a constant, and it fluctuates according to what we focus our attention on.
We have already been sanctified in our born-again spirits, once and for all, and we are progressively reproducing that sanctification in our actions day by day.
Note 7 at 1Th 4:3: In 1Co 6:18, Paul said to flee fornication, and in this verse, he said it is God's will that we abstain from fornication. The only way we will successfully abstain from fornication is to flee from it. Those who flirt with sin will succumb to it. The only sure way to overcome temptation is to avoid it (see notes 14-15 at 1Co 6:18).