When we have become born-again children of God by receiving Jesus into our hearts there is a part of us that has been born of an incorruptible seed and cannot sin or die and we will be children of God forever.
1 Peter 1:23 Being born again, not of corruptible seed, but of incorruptible, by the word of God, which liveth and abideth for ever.
1 John 3:9 Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God.
However for we still have a sinful flesh that can and does sin.
2 Corinthians 4:7 But we have this treasure in earthen vessels, that the excellency of the power may be of God, and not of us.
Galatians 5:16 This I say then, Walk in the Spirit, and ye shall not fulfil the lust of the flesh. 25 If we live in the Spirit, let us also walk in the Spirit.
John 8:11b go, and sin no more.
God helps us to avoid sinning and will forgive us when we fail. If eternal life only lasted until our next sin it would not be eternal. It was eternal in him and now it is eternal in us. He wants to guide us from His position in our hearts which He has purified.
Ephesians 3:17 That Christ may dwell in your hearts by faith; that ye, being rooted and grounded in love,
Acts 15:9 And put no difference between us and them, purifying their hearts by faith.
1 Corinthians 10:13 There hath no temptation taken you but such as is common to man: but God is faithful, who will not suffer you to be tempted above that ye are able; but will with the temptation also make a way to escape, that ye may be able to bear it.
1 John 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
The apostle John was certainly saved and on his way to heaven and included himself among us who will sometimes walk in the flesh and sin. When we get to heaven there shall be no Devil, no temptation and we shall be incapable of sinning ever again.
Revelation 21:27 And there shall in no wise enter into it any thing that defileth, neither whatsoever worketh abomination, or maketh a lie: but they which are written in the Lamb's book of life.
