In Genesis 2 and Matthew 19, God defines marriage as being between a man and a woman who leave their parents, join together, and become one flesh.  This becoming one flesh is understood to be directly related to the act of sex.  I Corinthians 6:15-16 make this clear.  In this passage, Paul tells the Christians not to participate with a prostitute, because in doing so they become one flesh with her.  Sex, or becoming one flesh with another, is to occur only in marriage.  This is God’s sexual boundary.

Paul goes on in verse 18 to tell the Christians to flee sexual immorality; that is, any sex outside of God’s boundary.  And he gives three reasons to flee: sexual immorality desecrates the body of Christ (v15-16), degrades one’s own body (v18), and in doing so desecrates God’s temple (v19-20).  We need to take this seriously.

None of this should need to be said.  But we need to be reminded because we live in a world where people hitch up for one night stands, dating couples sleep together, and unmarried couples live together.  But God has called Christians to be different.  We are to be holy as he is holy.  We are to hold to his boundaries.

And that means more than just abstinence.  Colossians 3:5 tells us:

Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry.

God’s boundaries mean we don’t want to possess another person (covet them).  It means we don’t lust after them (evil desires and passions).  It means we don’t act on those lusts (impurity).  All of these things, as well as sexual immorality, must be put to death.

That means single people must guard their minds and hearts from coveting and lust.  They must say no to these temptations.  Rather than see how close to the edge they can get without committing sexual immorality, they must put it to death long before it gets to that point.  They must embrace God’s sexual boundaries.  They must keep themselves pure.

That means people with homosexual tendencies must guard their minds and hearts from coveting and lust.  They too must say no to these temptations, as well as temptations further down the path.  They must embrace God’s sexual boundaries.  They must keep themselves pure.

That means that married people must guard their minds and hearts.  Should their eye or mind or heart start to drift toward someone other than their spouse, they must put that temptation to death.  They too must embrace God’s sexual boundaries.  They must keep themselves pure.

No matter what position in life we find ourselves, we must flee sexual immorality.  We must embrace God’s sexual boundaries.  We must be holy as God is holy.