The importance of walking in the light is clearly seen in 1 John 1:5-7.

1 John 1:5–7 (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.  ⁷ But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.

There have always been some who claim to be followers of God who teach some kind of message that indicates God tolerates sin.  In John’s day, it was those who would eventually be known as Gnostics.  In our day, they are those who claim we cannot lose our salvation no matter what we do or how we live (Calvinists) and those who teach we are saved by the finished work of Christ on the cross (faith alone advocates).

How we live does matter.  Why?  Because “God is light, and in Him is no darkness at all.”   God is impeccably pure.  He cannot tolerate sin, let alone have fellowship with it.  Therefore, John emphasizes that we are liars if we claim to have fellowship with God while walking in darkness.  On the contrary, if we walk in the light, fellowship with God is guaranteed.

How do we walk in the light?  This is an important question, seeing that our fellowship with God depends on it.  It begins with obeying the gospel.  Obeying the gospel results in our sins being washed away by the blood of Christ (Romans 5:9).

The blood of Christ is contacted when one is baptized.  This is where one’s sins are washed away.

Acts 22:16 (ESV)
¹⁶ And now why do you wait? Rise and be baptized and wash away your sins, calling on his name.’

This truth is validated by Paul when he taught that baptism is necessary to walk in the newness of life (Romans 6:4).  Paul tells us that this was the very purpose that he was baptized.  Newness of life is experienced because the person who obeys the gospel is no longer burdened by sin.  This is the imperative point concerning fellowship with God.  Newness of life and fellowship with God go hand in hand, being accomplished at the same time, that time being when one obeys the gospel.

This fellowship, however, must be maintained, something that is done by walking in the light.  The word “walk” in 1 John 1:7 is a present tense verb in the active voice, suggesting to us continuous action.  From the moment the blood of Christ originally washes away our sins, we must continue to walk in the light.  We do this by living by God’s Word.  This means obeying all His commandments as delivered to us by the law of Christ.  Failing to do so is a sin (1 John 3:4).

The Bible tells us several ways we must walk.  We must walk by faith (2 Cor. 5:7).  We must walk by the Spirit (Galatians 5:16).  We must walk worthy of our calling (Ephesians 4:1).

To walk by faith is to live by the Word of God since faith comes by hearing the Word (Romans 10:17).  To walk by the Spirit is to live by the Word of God as well since the Spirit is the revelator of the Word (John 16:13; 1 Corinthians 2:12-13).  To walk worthy of our calling is also to live by the Word since we are called by the gospel (2 Thessalonians 2:14).

All of this is involved in walking in the light, and it is what we must do to maintain our fellowship with God.  Does how we live matter?  It obviously does.  Do not be fooled by false teachers who teach a doctrine suggesting that God will tolerate sin in the form of disobedience to God.  As God said to the exiles through Jeremiah, “I have not sent them” (Jeremiah 29:9).

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