The question is not whether a believer can lose something he did not earn and had to be given by God through faith, the question is was a person who has no conscience over sin and uses grace as an excuse to sin, has ever been born again.
God never commanded us to ask forgiveness for sin after we were saved, however He did tell us to confess our sin. We cannot grow in grace if we will not confess that we are a sinner, and we cannot grow away from any particular sin unless we can openly confess we have a problem.
David asked the Lord to forgive him for unknown sin. We cannot be sinless in our bodies. Christ is our righteousness, not us or our good deeds. For the believer with unconfessed sin, he will lose fellowship and rewards in heaven, even suffer consequences in this life, but he does not lose his salvation, or the Holy Spirit.
If someone could lose their salvation over sin then no one would be saved. We all sin, if only in attitude or hidden sins of the heart. Unless anyone can tell me the size of sin, or the number of sins or the duration of sin for which God would remove His Holy Spirit, I stand on the Word that we cannot lose it.
I see no indication in the New Testament that described the leaving of the Holy Spirit from someone who was born again.
I must admonish anyone who thinks they never sin, even the tiniest of sins cannot be in the presence of our Lord, which is why He has imputed our sins to Christ.
How can a mere man, whom God says is desperately wicked do anything that would please God. We cannot, only Christ in us is righteous.
Romans 3:10 "As it is written: "There is none righteous, no, not one;"
2 Peter 1:1 "Simon Peter, a bondservant and apostle of Jesus Christ, To those who have obtained like precious faith with us by the righteousness of our God and Savior Jesus Christ:"
It has always been God's righteousness that saved a people from themselves. Nothing they could do in obedience means anything if apart from Christ.
Daniel 9:16 ""O Lord, according to all Your righteousness, I pray, let Your anger and Your fury be turned away from Your city Jerusalem, Your holy mountain; because for our sins, and for the iniquities of our fathers, Jerusalem and Your people [are] a reproach to all [those] around us."
When we realize that all our striving to be good is disgusting to God and it is only a faithful servant who can say "it is all you Lord", who will move forward in cleansing.
God will not cleanse the heart of a person who refuses to admit the need for cleansing and from someone who refuses to confess it.
