If a Christian does not repent of his sins, who are they ?
All Christians Sin ! and must repent of there sins and if they refuse to, they are of Satan's works.
When one is truly born again you can recognise Sin much better, not to mention that you can deal with Sin much better, because you know such is a Sin and can deal with such temptations because you will not be lead astray.
One who is lost can not deal with the temptations of Sin much at all, nor do they recognise such. as we see with the world nowadays, that they are falling into temptations of Satan and are puffed up with their own pride, that even Abortions on demand are seen as a pride that they see as honourable, when in fact it's Satanic and Same sex claiming to be a Marriage, when in fact it's Satanic, not to mention that if any Christian does not believes such is now not a Sin is fooling themselves and will go to Hell for claiming such is not a Sin, because the works of Satan lead the whole world astray, as that's what Satan's works are all about. so if one abides in Sin you are lost to Sin regardless if you think that you are born again or not.
One can not be truly Born Again and stoop down that low in fact. such is just religious works and following trends like a darn fools and that's why one must come out from among them types and look to Jesus Christ first and foremost in you lives 24/7.
The Kingdom of God does not have such Sinners within it, because they don't cut the grade, they are outside of it, with the dogs living under Sin looking for the 2ed coming because they are lost in their Sin. they have turned their backs on God for Political Correctness mans works nonsense that puffs them up, they think that man is going to cut the mustard and that's why they are looking to the so called Jews, fact is the Jesus never cut the mustard, that was only Jesus Christ that can cut it with God and no other man ever will.