If we want to have fellowship with God, we must be holy.  Remember, God is morally perfect and cannot tolerate any kind of sin.  John wrote about this in his first epistle.

1 John 1:5-6 (ESV)
⁵ This is the message we have heard from him and proclaim to you, that God is light, and in him is no darkness at all.  ⁶ If we say we have fellowship with him while we walk in darkness, we lie and do not practice the truth.

God wants us to be holy because He is holy (1 Peter 1:15-16).  While we are not morally perfect like He is, we can do our best to remain morally pure by living holy lives.  Holiness has to do with living a sanctified or separated life.  To be holy, then, is to separate ourselves from things that are displeasing to God.  This is holiness that is precipitated by us.  We call this “progressive holiness.”  “Positional holiness” is what God did to us when we obeyed the gospel.  This is why Peter indicated that we are sanctified (made holy) by the Spirit (1 Peter 1:2).  God moved us from the darkness of the world into the kingdom of His beloved Son when we obeyed the gospel (Colossians 1:13).  Now, however, it is up to us to complete our holiness by living lives of purity.

2 Corinthians 7:1 (ESV)
¹ Since we have these promises, beloved, let us cleanse ourselves from every defilement of body and spirit, bringing holiness to completion in the fear of God.

The challenge we face in accomplishing this is to not give in to the things that are popular with the world.  We cannot be holy if we are unwilling to be different from the majority.  Being different is a recurring theme in the New Testament.

Romans 12:2 (ESV)
² Do not be conformed to this world, but be transformed by the renewal of your mind, that by testing you may discern what is the will of God, what is good and acceptable and perfect.

To conform to this world is to act in agreement with it, and when we do that in areas that are contrary to the will of God, we cease to be holy.  We must remain separated from the world by godly behavior (2 Corinthians 6:14-18).  For example, let us not conform to this world in our speech.  Paul once exhorted Christians to not allow corrupt communication to proceed out of their mouths (Ephesians 4:29).  Instead, our speech needs to be seasoned with salt (Colossians 4:6).  This means we must avoid things like gossip, sarcasm, rudeness, and, of course, bad language.

Colossians 3:8 (ESV)
⁸ But now you must put them all away: anger, wrath, malice, slander, and obscene talk from your mouth.  

Another example by which we can demonstrate holiness is by our dress.  This is difficult because most people today dress immodestly.  To complicate things further, it is hard to even find modest clothing in our stores today.  It takes determination to be holy in this area – the same kind of determination that Daniel demonstrated when he was instructed to eat at the king’s table.  He refused to do it, not wanting to defile himself before God (Daniel 1:8).  It is noteworthy that Daniel resolved not to do this.  Being holy is not something that happens by accident. We must make up our minds that this is what we want to be.  Once we do that, we will not wear clothes that God would disapprove of, even though they are popular with the people around us.  We must avoid things like jeans that are too tight, blouses that are too low, or shorts that we too short (1 Timothy 2:9).

Let us do our best to live up to the moral standard of the Word of God.  This may not be popular, but our habitual holiness will please God and there is nothing more important than that.

As you wind down for the night, think about these things.