Once a person is born again, becoming a child of God, being saved having eternal life, does that mean they never sin again?
While there are some Christians (though a minority) that defend "sinless perfectionism", most take a position of what's referred to as "habitual sin" from the tense of the verb in the Greek, and the translations that say "practicing sin" as a distinct concept from committing any sin at all.
Let's start by looking at the wider context:
The Word of God says in 1 John 3:1–2 (NKJV):
Behold what manner of love the Father has bestowed on us, that we should be called children of God! Therefore the world does not know us, because it did not know Him. Beloved, now we are children of God; and it has not yet been revealed what we shall be, but we know that when He is revealed, we shall be like Him, for we shall see Him as He is.
First and foremost, it is imperative to identify the audience being addressed. The author is clearly speaking to the children (or sons) of God, a title consistently ascribed to believers throughout Scripture.
Galatians 3:26 (NKJV) says:
For you are all sons of God through faith in Christ Jesus.
Likewise, John 1:12 (NKJV) declares:
But as many as received Him, to them He gave the right to become children of God, to those who believe in His name.
Before examining the distinction in 1 John 3:6, it is essential to acknowledge that all believers still struggle with sin in this life.
1 John 1:8 (NKJV):
If we say that we have no sin, we deceive ourselves, and the truth is not in us.
This verse is written in the present tense, affirming that even those who walk in the light (see verse 7) still sin.
Romans 3:23 (NKJV):
For all have sinned and fall short of the glory of God.
This again is in the present active sense—“fall short”—indicating a continual condition in the flesh.
Now consider 1 John 3:6 (NKJV):
Whoever abides in Him does not sin. Whoever sins has neither seen Him nor known Him.
Here a dichotomy is introduced—between one who does not sin and one who does. This might seem confusing at face value, especially for any believer who is honest about their struggle with sin. However, the Apostle Paul speaks directly to this issue of two conflicting natures within the believer in Romans 7:
Romans 7:18–25 (NKJV):
For I know that in me (that is, in my flesh) nothing good dwells; for to will is present with me, but how to perform what is good I do not find. For the good that I will to do, I do not do; but the evil I will not to do, that I practice. Now if I do what I will not to do, it is no longer I who do it, but sin that dwells in me. I find then a law, that evil is present with me, the one who wills to do good. For I delight in the law of God according to 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 will deliver me from this body of death? I thank God—through Jesus Christ our Lord! So then, with the mind I myself serve the law of God, but with the flesh the law of sin.
Paul draws a sharp distinction between:
the flesh, which cannot please God and continues in sin
the inward man, which delights in God’s law and serves Him
This is key to rightly dividing 1 John 3.
2 Corinthians 5:17 (NKJV) reinforces this distinction:
Therefore, if anyone is in Christ, he is a new creation; old things have passed away; behold, all things have become new.
There is an old man and a new man. One sins; the other is born of God.
Returning to 1 John 3:6–9 (NKJV):
Whoever abides in Him does not sin. Whoever sins has neither seen Him nor known Him. Little children, let no one deceive you. He who practices righteousness is righteous, just as He is righteous. 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. 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.
This passage is not claiming that a Christian will never commit an act of sin in the body. Rather, it is referring to the part of the believer that is born of God—the new man, the inward man—which, as Paul says, delights in the law of God and cannot sin.
Why? Because:
My body is not born of God and serves the law of sin.
My spirit, the new man, is born of God and cannot sin.
Every believer has these two natures:
the outward man and the inward man
the old man and the new man
the body of this death and the spirit that delights in God
The flesh and the spirit are always at odds.
Galatians 5:16–17 (NKJV) explains this:
I say then: Walk in the Spirit, and you shall not fulfill the lust of the flesh. For the flesh lusts against the Spirit, and the Spirit against the flesh; and these are contrary to one another, so that you do not do the things that you wish.
This daily battle requires a daily choice: walk in the Spirit, or walk in the flesh.
Do not be discouraged, and do not give up. Even if you struggle, you have the power through the Spirit to walk in righteousness.
"Walk in the Spirit, and you shall not fulfill the lust of the flesh."