Jesus answered and said to him, “Truly, truly, I say to you, unless one is born again [from above] he cannot see the kingdom of God. (John 3.3, NASB)
The “sinner saved by grace” bumper sticker prominently displayed on a disproportionate number of beat-up Chevettes belies a fundamental misunderstanding of the essence of the Gospel. You usually find those Chevettes parked at churches where the preacher implores the audience each Sunday to “come to God” by kneeling at the altar and confessing that they are indeed sinners. After some heartfelt sobbing, the confessor is considered to have “prayed through” and he is a “saved” man. When this “saved” man comes back the next Sunday, although God has supposedly forgiven him, he is browbeaten again by the preacher. This time around he’s “saved by grace,” but he is still a despicable sinner who ought to know just how he’s continually failed God between Monday and Saturday. This approach to salvation is foreign to the New Testament epistles.
The issue for that unsaved man is not the forgiveness of any particular sins. And it doesn't have anything to do with him repenting enough so God will take him in. The crux of the problem is his nature. As a sinner, he is a child of wrath who hasn’t the ability nor the right to ask a thing from God.
in which you formerly walked according to the course of this world, according to the prince of the power of the air, of the spirit that is now working in the sons of disobedience. Among them we too all formerly lived in the lusts of our flesh, indulging the desires of the flesh and of the mind, and were by nature children of wrath, even as the rest. (Ephesians 2.2-3, NASB)
Unless this diabolical nature is changed, forgiveness of particular sins is irrelevant.
When one goes to the New Testament epistles which lay out the how-to for the born-again nature Jesus spoke of to Nicodemus, there is no sinner’s confession of sins, requisite godly sorrow, or repentance to be found. There is, instead, another kind of confession:
that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised him from the dead, you will be saved. (Romans 10.9, NASB)
The unsaved man doesn’t confess that he’s a sinner before God in order to get saved. He confesses a different lord —Jesus—and that dreadful nature of his is transfigured:
Therefore if anyone is in Christ, he is a new creature; the old things passed away; behold, new things have come. Now all these things are from God . . . (2 Corinthians 5.17, 18a, NASB)
This born-again experience is not theological righteousness, a reckoned righteousness, or even an imputed righteousness. It's the infusion of God’s own life, his own righteous nature into a man's inner self. The unregenerate child of wrath becomes the very workmanship of God (Ephesians 2.10 - “For we are His workmanship created in Christ Jesus”). And it's because of this new birth, “Christ in you, the hope of glory,” that the saved man is not a sinner anymore. There should not be any misunderstandings along these lines.