I think that a person who believes they are past sinning lacks self-awareness, and presumes things they do not know.
Believers should be in a Sanctification Process of living more progressively holy by the Spirit (2 Corinthians 7:1), until they overcome sin in this life (Galatians 5:24) (1 Peter 4:1-2).
A slave to sin will not abide in the house of Christ forever (See: John 8:34-35). What does this mean? Matthew 13:41-42 tells us in that the Son of Man (Jesus) will send forth His angels, and they will gather out of HIS Kingdom all who do iniquity and they will be cast into the furnace of fire (i.e. the Lake of Fire).
Beyond that, you must have a very different idea of what being born again is from what I think, because this "on again off again" rebirth, I don't find this in the Bible in the least.
John 8:39 KJB
“If ye were Abraham’s children, ye would do the works of Abraham.—“
1 John 2:29 KJB
“…ye know that every one that doeth righteousness is born of him.”
1 John 3:10 KJB
“In this the children of God are manifest, and the children of the devil: whosoever doeth not righteousness is not of God, neither he that loveth not his brother.”
1 John 4:7-8 KJB
7 “Beloved, let us love one another: for love is of God; and every one that loveth is born of God, and knoweth God.
8 He that loveth not knoweth not God; for God is love.”
1 John 5:2 KJB
“By this we know that we love the children of God, when we love God, and keep his commandments.”
Matthew 8:12 KJB
“But the children of the kingdom shall be cast out into outer darkness: there shall be weeping and gnashing of teeth.”
In the Parable of the Prodigal Son: When the son came home from living it up with prostitutes, and he sought forgiveness with his father, his father said he was dead, and he is alive again. He was lost and now he is found (See: Luke 15:24, and Luke 13:32). The prodigal son did not die physically, and so it is talking in spiritual terms. The son died spiritually while living it up with with prostitutes and he became alive AGAIN spiritually when he came back home and sought forgiveness with his father. This same truth is taught in James 5:19-20. We learn that if any brethren errs from the truth, and they convert them back, they should know that they helped save a soul from death, and they helped to cover a multitude of sins. Meaning, if a fellow believer went prodigal into sin, and you helped to rededicate their life in following Jesus again and get them to seek forgiveness with the LORD Jesus, then you would have saved their soul from death.
Luke 8:21 KJB
“And he answered and said unto them, My mother and my brethren are these which hear the word of God, and do it”
Jude 1:12-13 KJB
12 “These are spots in your feasts of charity, when they feast with you, feeding themselves without fear: clouds they are without water, carried about of winds; trees whose fruit withereth, without fruit, twice dead, plucked up by the roots;
13 Raging waves of the sea, foaming out their own shame; wandering stars, to whom is reserved the blackness of darkness for ever.”
These types do not fear God, and they are without fruit, and they are twice dead. They are twice dead because they were once dead spiritually before coming to Christ, and they are dead spiritually a second time by later justifying sin. Jude 1:4 (NIV) says there are ungodly people who pervert the grace of our God into a license for immorality (KJB says: turning the grace of our God into lasciviousness).
Jesus warned how certain sins can keep you out of God’s kingdom (Matthew 5:28-30) (Matthew 6:15) (Matthew 12:37) (Matthew 25:31-46). The apostle Paul said if any man does not agree with the words of Jesus Christ and the doctrine according to godliness, he is proud and he knows nothing (1 Timothy 6:3-4). James 4:6 says God resists the proud and gives grace to the humble.
Even the apostle Paul said,
“But if any provide not for his own, and specially for those of his own house, he hath denied the faith, and is worse than an infidel.” (1 Timothy 5:8).
Call it justifying sin, making excuses for sin, those are all your words, not mine.
Much love!
Jeremiah 22:23 says,
”But if they had stood in my counsel, and had caused my people to hear my words, then they should have turned them from their evil way, and from the evil of their doings.”