There are at least 3 Bible passages that list specific sins that would prevent a person from inheriting the kingdom of God. It would seem like either truly born-again Christians would not practice those sins, or Christians who practice those sins would not be saved.
Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God. (1 Corinthians 6:9-10 NKJV)
Blessed are those who do His commandments, that they may have the right to the tree of life, and may enter through the gates into the city. But outside are dogs and sorcerers and sexually immoral and murderers and idolaters, and whoever loves and practices a lie. (Revelation 22:14-15 NKJV)
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 NKJV)
According to Apostle John, there is sin that lead to death and there is sin that doesn't. I wonder if he was referring to willful sins or specific sins listed above.
If anyone sees his brother sinning a sin which does not lead to death, he will ask, and He will give him life for those who commit sin not leading to death. There is sin leading to death. I do not say that he should pray about that. All unrighteousness is sin, and there is sin not leading to death. (1 John 5:16-17 NKJV)