What you are saying has been taught in the church for centuries. But that is not what the apostles preached.
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. 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.
So when the Holy Spirit came in you, you immediately stopped sinning? You are deceiving yourself. This sin is not sin unto death I'm talking about. Our sins past, present and future have been forgiven. I hate to burst your bubble, but you are not perfect. No Christian becomes perfect. What actually happens is you are washed of your sins and your spirit becomes alive when you are born again. Your spirit remains pure, it has to, this is where the Holy Spirit dwells in you. However, you still have the fleshly part of you, where sin dwells. That part of you is sanctified but not instantly, if takes a lifetime or spiritual growth.
Do you really think you are without sin and spiritually mature? No, sorry. I was confused about this very thing when I first became a Christian. Why do think Catholics go to confession every week? Do you think the whole Catholic church is confused about this? I don't know what church you sit in or who teaches you but they are teaching you wrong. The Bible commands us to confess our sins to one another.
Romans 6:12 speaks to the Christian: "Therefore do not sin reign in your mortal body, that you should obey it in its lusts." Sin doesn't have power over us but we are able to fall back (backslide) into our old self again.
Again to the Christian: "Do not present your members as instruments of unrighteousness to sin, but present yourselves to god as being alive from the dead..."vs13
Paul said, "BUT NOW, IT IS NO LONGER I WHO DO IT, BUT SIN THAT DWELLS IN ME." Rom.7:17
Let me go through your 1 John 3 scriptures: vs 4 - He who commits sin/lawlessness. (This is speaking of those who
practice sin and have not come to the Lord) In verse 7 it speaks of those who
practice righteousness.
One does not practice sin unless he is a slave to it nor righteousness unless he is a slave to God. vs. 8 - "He who sins is of the Devil" (so Christ was manifest to destroy his works is just a snapshot of humanity and Christ's solution). I too got stuck on 1 John 3:9 for a long time until I realized, yes, I still break God's commandments on occasion. I'm not a slave to them, have been freed from bondage and judgment but I, like Paul have sin that dwells in the members of my flesh.