First of all, children of God do sin. This is not a theory or my personal logic. This is PROOF!
WE ARE PUNISHED
Hebrews 12:7-11
And ye have forgotten the exhortation which speaketh unto you as unto children, My son, despise not thou the chastening of the Lord, nor faint when thou art rebuked of him: For whom the Lord loveth he chasteneth, and scourgeth every son whom he receiveth. If ye endure chastening, God dealeth with you as with sons; for what son is he whom the father chasteneth not?
But if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons.
HOW CAN YOU BE PUNISHED IF YOU ARE FOLLOWING THE COMMANDS OF GOD?
Yet it is true that a born again Christian is sinless, BUT NOT IN THE SENSE YOU ARE THINKING.
When you are born again, the Holy Spirit regenerates your dead spirit. This revived spirit is called the new man or the inner man. Now the only thing not holy is your flesh, your old man. That will get glorified later to match your spirit. For the time being, this part of you DOES SIN, but this part is not counted as the REAL YOU. Paul talks about it like throwing off a tent or tabernacle. Now let me show you in scripture how this is the case.
Please key in on what I have put in Caps, it will help
Romans 7:14-24
For we know that the law is spiritual: but I AM CARNAL, sold under sin.
For that which I do I allow not: for what I would, that do I not; but what I hate, that do I.
If then I do that which I would not, I consent unto the law that it is good. Now then it is no more I that do it, but sin that dwelleth in me.
For I know that in me (that is, in my flesh,) dwelleth no good thing: for to will is present with me; but how to perform that which is good I find not.
For the good that I would I do not: but the evil which I would not, that I do. NOW IF I DO THAT I WOULD NOT, IT IS NO MORE I THAT DO IT, BUT THE SIN THAT DWELLETH IN ME. I find then a law, that, when I would do good, evil is present with me.
For I delight in the law of God after the inward man:
But I see another law in my members, warring against the law of my mind, and bringing me into captivity to the law of sin which is in my members.
O wretched man that I am! who shall deliver me from the body of this death?
Now it is important to note that Paul is talking in the present tense, this is not stuff from the past. If you need more proof of that particular point read this...
1 Timothy 1:15
This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save SINNERS; OF WHOM I AM CHIEF.
In the verse Paul says, "I AM CHIEF," and not, "I WAS CHIEF." I bring this point up because some will tell you that Paul was speaking about his former condition.
Now we are sealed with the Holy Spirit of Promise
Ephesians 4:30
And grieve not the holy Spirit of God, whereby ye are SEALED UNTO THE DAY OF REDEMPTION.
Sealed unto the day of redemption! Your inner man can not be tampered with until the flesh is glorified to match it.
Ephesians 1:13-14
In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, YE WERE SEALED with that holy Spirit of promise, Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory
Most Christians think they can actually go through life and never engage in wrongdoing after placing faith in Christ. However this is not what the scripture means when it says one born of God can not sin. THE REAL YOU, THE NEW MAN can not sin. You are still living in the flesh quite literally. Now you don't have to walk after the flesh, but the old nature will pull you down during this life. We struggle and that is why we confess our sins daily, because we commit them daily: our flesh that is.
I am not advocating carnality, I am just saying we are locked in a struggle and we should not act like the Pharisees and pretend like we do not need a physician. They could not see their sins, so their sins remained.
Jesus cuts us off from the fatal effects of the flesh would have on the spirit. This is the circumcision of Christ.
Colossians 2:11
In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the CIRCUMCISION OF CHRIST:
There is now a severing of spirit and body in terms of NATURE. Your morally corrupted body matched your morally corrupt spirit. They were both functionally dead. However upon belief, Christ regenerated your spirit in purity. Once this was done, he severed the flesh from it in terms of nature and power. So now they oppose each other. Foreskin is no longer living once removed from that which is living. It is no longer part of your member. In spiritual circumcision, it is a separation of impulse and desire. One desiring evil, and the other barring an impulse for good.
Read Paul scolding his church
1 Corinthians 3:3
For ye are yet carnal: for whereas there is among you envying, and strife, and divisions, ARE YE NOT CARNAL, and walk as men?
This is only insulting if you have two natures. Spiritual and carnal. No one repudiates a dog for it's carnal desires. It only has one nature. Now that we have two natures, one noble and one base, we are instructed to serve the noble.
-But to him that worketh not