7 Little children, let no one deceive you. He who practices righteousness is righteous, just as He is righteous. 8 He who sins is of the devil, for the devil has sinned from the beginning. For this purpose the Son of God was manifested, that He might destroy the works of the devil. 9 Whoever has been born of God does not sin, for His seed remains in him; and he cannot sin, because he has been born of God. 1 John 3:7-9
Our righteousness is found in Christ. But there is an outward righteousness that must be present in our lives if we are to truly be followers of Jesus Christ. Our lives should reflect the holiness and righteousness of who Jesus is. It is not biblical to claim to follow Christ and be a child of God but continue to live in sin.
Jesus came to destroy the works of the devil. Through His death and resurrection He overcame the curse of sin and death. When we come to Christ our lives are set free and the devil no longer has authority over our lives. So those who continue to live in sin and indulge in sin cannot be children of God. They may claim to follow Christ but the only thing that proceeds from their mouths is empty words.
Is it possible to walk in sinless perfection upon this earth, my thoughts and opinion is no. We can live lives that continually are transformed and matured into the character and image of Christ. But as long as we live on this side of Heaven we still have our fallen sinful nature. But through Christ sin no longer dominates or has dominion over our lives. Before we come to Christ we are dominated by sin and are driven to indulge and fulfill the lust of the sinful nature. But once we come to Christ we are led by the Holy Spirit and are called to follow the leading of the Holy Spirit. The Holy Spirit will convict our hearts when we are living in opposition to God’s will. If we are truly a child of God and follower of Christ we will heed the voice and leading of the Holy Spirit.