1 john 3: 4 Whoever commits sin also commits lawlessness, and sin is lawlessness. 5 And you know that He was manifested to take away our sins, and in Him there is no sin. 6 Whoever abides in Him does not sin. Whoever sins has neither seen Him nor known Him.
If the one who sins has never seen or known God, that means the one who sins has never been saved, never been adopted as children of God.
And since abiding is what makes us a people who do not sin, then it means those who abide must know God, and have been born of him, This is shown by the rest of what John said...
(of note. Sin in this passage is not singular. Or personal sins, it is written in a way that means a sinful life. A life of sin, ie, living the way the world life, in continuous habitual sin)
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. Who practices righteousness? But those who know what rue righteousness is? They are those who have been born of God
2. He who sins is of the devil. Ie, not born of God, still under satan, an outsider who has never been saved
3. Whoever has been born of God does not sin (this answered vs 6 as to who it is who abides in christ, and verse 7 as to who is is who practices righteousness. Ie, they are are not born of God because they do these things, but they do these things because they are born of God. Proven by the final statement, Because they have been born of God, they can NOT sin (practice unrighteousness)
does this help? Do you have any questions, I am not always clear I admit that failure.