[Winman]

Well, Rev 3:19 is written to believers, and it says to repent.

Rev 3:19 As many as I love, I rebuke and chasten: be zealous therefore, and repent.

This shows clearly that a saved person can be out of fellowship with Christ, and that Christ will rebuke them and chasten them. And the believers here are told to repent. I do not know how you repent of a sin without acknowledging and confessing that sin.

I see it no different than our earthly family. When I was a child I did some wrong things which grieved my father. He did not kick me out of the family, but he did rebuke and chasten me a few times.

And the Bible teaches this very thing.

Heb 12:1 Wherefore seeing we also are compassed about with so great a cloud of witnesses, let us lay aside every weight, and the sin which doth so easily beset us, and let us run with patience the race that is set before us,

So, while we may be saved, we still have a big problem with sin. And the Lord will chasten us for it.

Heb 12:4 Ye have not yet resisted unto blood, striving against sin. 5 And ye have forgotten the exhortation which speaketh unto you as unto children, My son, despise not thou the chastening of the Lord, nor faint when thou art rebuked of him: 6 For whom the Lord loveth he chasteneth, and scourgeth every son whom he receiveth. 7 If ye endure chastening, God dealeth with you as with sons; for what son is he whom the father chasteneth not? 8 But if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons. 9 Furthermore we have had fathers of our flesh which corrected us, and we gave them reverence: shall we not much rather be in subjection unto the Father of spirits, and live? 10 For they verily for a few days chastened us after their own pleasure; but he for our profit, that we might be partakers of his holiness. 11 Now no chastening for the present seemeth to be joyous, but grievous: nevertheless afterward it yieldeth the peaceable fruit of righteousness unto them which are exercised thereby.

So, Christians can surely sin, and it does not go unnoticed by the Lord. He will chasten us and correct us. If you see a person who sins continually without being chastened, then that person is not truly saved, for God chastens all his children whom he loves.