Some who profess to be Christians believe that how we live does not matter.  Sometime during the first century, this belief (an early form of what later became Gnosticism) turned doctrinal and had to be exposed as false.  John championed the cause in his epistles, condemning the idea that sinful behavior is okay.

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.

Later he wrote,

1 John 3:8-9 (ESV)
⁸  Whoever makes a practice of sinning is of the devil, for the devil has been sinning from the beginning. The reason the Son of God appeared was to destroy the works of the devil. ⁹  No one born of God makes a practice of sinning, for God’s seed abides in him, and he cannot keep on sinning because he has been born of God.

Avoiding sin is the endeavor of every Christian.  As Christians, we are not perfect, but, morally speaking, we should try to be.  This is one reason John wrote what he did in First John.  He was attempting to get Christians, who had been exposed to false teaching on this, to strive not to sin.  He wrote, “My little children, I am writing these things  to you so that you may not sin…” (1 John 2:1).  This should be the determination of us all.

While we were originally cleansed by the blood of Christ, remaining clean involves personal effort on our part.

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.

This is a daily venture.  The world around us is corrupted by sin.  Remaining pure in an impure environment takes a fixed purpose.  We need to have the mindset of Daniel.  He purposed in his heart not to defile himself (Daniel 1:8).  Have you made being pure and undefiled the purpose of your heart?  To be like Daniel, we must not allow the world to rub off on us (Romans 12:2).  Let us always remember the words of James.

James 1:27 (ESV)
²⁷  Religion that is pure and undefiled before God, the Father, is this: to visit orphans and widows in their affliction, and to keep oneself unstained from the world.   

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