I don’t know of any verse that teaches that a born again Christian somehow goes back to being un-born again.
A born again Christian can certainly return to practicing the works of the flesh, rather than living according to the Spirit.
Paul teaches this throughout his letters.
First Paul tells them that if they walk according to the Spirit, they will not fulfill the lustful desires of the flesh.
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.
But if you are led by the Spirit, you are not under the law.
Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness, idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that
those who practice such things will not inherit the kingdom of God. Galatians 5:19-21
- of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God
Do you know what the phrase will not inherit the kingdom of God means?
Paul constantly warned of this over and over to all the Churches.
- of which I tell you beforehand, just as I also told you in time past
JLB