John is contrasting the claims of some who are not believers but say that they are, with the lives of those who are truly the children of God.
The first category has no knowledge or conviction of sin. They say they have fellowship with the God Who is Light, and yet their lives are unchanged and they actually walk in the darkness of sin. They say that they have no sin and have not sinned but in doing so they are deceiving themselves and calling God a liar, since God says all have sinned and come short of His glory. Of these people, John concludes, God's Truth and His word is not in them.
In contrast, the true believer walks in the Light, has fellowship with other believers and is cleansed from all sin by the blood that Jesus shed on the cross. Walking in the light means that their sins will be exposed but God has provided a way that this consciousness of sin, and the hindrance to fellowship with God that it produces, can be dealt with - confession. Our text contains a wonderful promise for the believer. It says that because of what Jesus has done, God can be faithful and righteous to forgive our sins and cleanse us from all unrighteousness if we confess our sins to Him. So the life of the true believer is one of conviction of sin produced by the Spirit through the Word, leading to confession and cleansing. This is the pathway to godly living.
For our encouragement to pray this week, though, let us focus on the fact that we may come to God, indeed we are urged to come, and confess our sins before Him, knowing that we will not meet with wrath and rejection but with forgiveness and cleansing. Why would we not want to come to God given such a promise as this?
Note, also, the inclusive nature of the sins and the unrighteousness that are cleansed away through confession. It is not some of our sins and blots and blemishes, while others remain to plague our consciences and disturb our peace - it is the totality, the entirety of our offenses that are covered and cleansed through the work of Jesus!
What a difference between the condition of unbelievers and believers! What a different view of themselves and of God, and what a different result from their differing approaches to Him!
Believer, if you would know a closer walk with God in this coming week, confess your sins to Him and receive the promised cleansing! Take the opportunities that the Lord supplies and keep a short account with the Lord.