I Thess. 4:7-8 God has called us to be holy, not to live impure lives. Anyone who refuses to live by these rules is not disobeying human rules but is rejecting God, who gives his Holy Spirit to you.
Life's greatest calling is to be a holy people. Every believer in Christ is called to be holy. It is not enough to proclaim ourselves as being holy because He is holy. Talking about being holy and actually being holy are two different things. A holy people are a people who are becoming like Christ in character, thought, and action. We will never achieve Christ-like holiness on earth, but we can continue our progression towards it. We must measure ourselves by the standards of God's Word. We must strive to be far more like God than like the world. We must not settle for mediocrity in our Christian walk. In fact, I do not believe a true child of God cannot live in Christ without growing into holiness.
Life's greatest challenge is to a holy people. We live in an unholy world, surrounded by an unholy people. We have opportunity to sin all the time. We are constantly challenged to think as the world thinks about things. We are challenged to take the necessary time with the Lord to be a holy people.
We too easily excuse lack of spiritual growth in our walk with the Lord. We rely on His holiness and think it's okay to be who we are because we trust in Him. It is not okay to live in mediocrity! God created us in Christ to be a holy people, a people after His own heart and like Him in character. If we fail to strive for holiness in our lives, we are rejecting God's plan for us. We are rebelling against Him and denying Him His rightful place in our lives.
Let us always be moving into greater holiness. With the Lord in control of our hearts and minds, we can do it. It is not an option, it is a command from God.