If we say that we have not sinned, we make Him a liar and His word is not in us.1 John 1:10(NASB)
While John's gospel was written so that lost sinners might believe in the saving blood of Christ, be forgiven of their trespasses, be redeemed from the slave-market of sin, and have life in His name, the purpose of his first epistle is to enable born-again saints to enter into the fullness of the eternal life we received at salvation. This equips the believer to have fellowship with other Christians and enjoy sweet communion with God the Father and our Lord Jesus Christ.
Only by faith can lost sinners be justified. Only someone born of the Spirit can enjoy fellowship with the Father and walk in His marvellous light. Only those who are saved by grace through faith in Christ, are forgiven of all their sin and declared righteous in the sight of God. How we praise our heavenly Father that at the moment of our salvation, past, present, and future sins are forgiven forever, and will be remembered no more.
However, the forgiveness of our sin at salvation does not make us sinless beings, nor do we stop sinning. We inhabit a fallen body which is not yet glorified. Although we have a new nature, (our new-life-in-Christ), we are gradually being sanctified in Him as we grow in grace and in a knowledge of the Lord Jesus. Progressive sanctification takes place in the lives of all believers, as we are conformed into the image and likeness of the lovely Lord Jesus, until we are fully sanctified - spirit, soul, and body, when we finally go to be with Him.
Despite the assurance that we will receive a new, glorified body at the Rapture (the resurrection of Church-age saints), the old sin nature will continue to lust against our new-life-in-Christ during our sojourn on earth, and for the rest of our life it must be kept nailed to the Cross, if we are to maintain close communion with the Lord.
Salvation assures us of eternal life and a heavenly inheritance, for all God's promises are 'yes' and 'amen' in Christ... but we do not reach 'sinless perfection', as some like to preach. We are clothed in Christ's righteousness - not our own righteousness. Our sins were forgiven because of HIS shed blood at Calvary. Our salvation is not dependent on our own efforts or greatness, but rests entirely upon Him.
The false teaching of 'sinless perfection', that is so popular with those that consider salvation is a license to sin, is firmly refuted in this verse, "If we say that we have not sinned, we make God out to be a liar and His word is not in us." John is speaking to believers in this verse - If WE Christians say that we have not sinned, because we are clothed in Christ's righteousness and declared righteous by God through faith, THEN WE Christians make Him out to be a liar and His Word (of truth) is not in us.
Only an unbeliever or proud religionist could make such a statement. Only a self-righteous, legalistic sinner, could be arrogant enough to claim that he has not sinned, or that he is good enough to merit heaven! Those who KNOW the truth of the glorious gospel of grace could never make such a claim, for we are not saved because of OUR goodness but because of HIS goodness. We are not declared righteous by the good deeds that we have done but by HIS blood - shed for you and me. We are sinners, saved by grace, and not by any works of our own righteousness.
Some preachers have misinterpreted this verse because they have misunderstood John's earlier statement, "If we say that we have fellowship with Him and yet walk in the darkness, we lie and do not practice the truth." They teach that if a Christian sins, then they were never saved in the first place OR that they have lost their salvation!! But this epistle is not about the justification of an unbeliever. This letter is about the sanctification and fellowship a believer can enjoy when they are walking in spirit and truth and not living a carnal lifestyle.
John is not talking about initial salvation, when we are saved by grace through faith. This teaching is about born-again Christians maintaining FELLOWSHIP with the Father, by walking in spirit and truth and confessing our post-salvation sins. May we take to heart this beautiful truth and determine, in His strength, to remain low at the Cross in humility of heart, and broken before Him.
Heavenly Father, how I praise and glorify Your holy name that my sins are forgiven by faith in Christ, and that I can enjoy sweet fellowship with You. I confess I have no righteousness of my own and do not deserve to receive Your grace and favour. But thank You that my hope rests on Christ. Dear Father, too often I find myself allowing fleshly tendencies to influence my life choices. Forgive me for the times I have left my first love, behaved arrogantly, or failed to listen to Your gentle promptings. Restore to me the joy of my salvation. In Jesus' name I pray, AMEN.