"Now I rejoice, not that you were made sorry, but that your sorrow led to repentance. For you were made sorry in a godly manner [convicted in heart - seeing sin as God does], that you might suffer loss from us in nothing. For godly sorrow produces repentance leading to salvation, not to be regretted; but the sorrow of the world [self-centered] produces death. For observe this very thing, that you sorrowed in a godly manner: What diligence it produced in you, what clearing of yourselves, what indignation, what fear, what vehement desire, what zeal, what vindication [justification]! In all things you proved yourselves to be clear [lit. "PURE"] in this matter." -2 Corinthians 7:9-11

The Bible says that godly sorrow produces repentance, which leads to salvation (purity) but the sorrow of the world produces death (Hebrews 12:17; Matthew 27:3). [false repentance is based simply on emotion or intellect and is worried about personal interests more than how your sin effects God and others, and is not from sincerity of heart]. Then Paul goes on to describe the qualities of this repentance which is produced by "godly sorrow" and ends in justification, purity and salvation:

Conviction at the hearing of God's Word/the Gospel...

Godly Sorrow experienced in the good and noble heart which has properly received the Word of God (Luke 8:15)...

And... REPENTANCE:

Diligence [speed, haste; earnest effort to change and be cleared]...
Clearing of yourself [of wrongdoing and making amends where possible; self-vindication, self-defence]...
Indignation [hate/anger of personal sin; self-contempt, disgust or abhorrence]...
Fear [godly fear; fear of God; conviction of heart; fear of sinning more]...
Vehement Desire [intense passion; ernest longing for reconciliation with God;  longing for restoration]...
Zeal [enthusiastic diligence to remove sin; eagerness in embracing and pursuing these things]...
Vindication [to avenge, to do justice]
Clear [Greek, “pure”]...

THEN ---> Salvation!
The above outlined qualities are all ingredients of true Biblical Repentance. In light of this, repentance could be looked at as beginning with a "crisis of conviction" where one, if they allow them-self in humility (James 1:21), experiences a "season of godly sorrow", which then leads to "a clearing", or a "time of refreshing" (Acts 3:19) and finally comes clean with the Lord and thus purifies their soul (1 Peter 1:22). THEN they can come into contact with Christ's Blood and receive forgiveness [a clear; pure heart], and where they come into initial salvation and forgiveness of past sins (Rom. 3:25). 

Biblical repentance is a real change, far beyond simply "believing, confessing or desiring" (like what is taught in the majority of churches, and has been for hundreds of years). Repentance is where the old man dies in the "baptism of death", or the "baptism of repentance", and thus where the passions and desires of the flesh are crucified, where the circumcision of the heart takes place (Colossians 2:11; Romans 2:29), and the New Birth occurs (John 3:3; Ephesians 4:24):

Romans 6:3-5
Or do you not know that as many of us as were baptized into Christ Jesus were baptized into His death (taking up the cross - Mat.10:38). Therefore we were buried with Him through baptism into death (crucifying passions and desires of the flesh - Galatians 5:24; 1 Peter 4:1), that just as Christ was raised from the dead by the glory of the Father, even so we also should walk in newness of life (2 Cor. 5:17; Eph. 4:24). For if we have been united together in the likeness of His death, certainly we also shall be in the likeness of His resurrection. 

True Biblical Repentance, therefore, will include a turning FROM sin, a turning TO God, which are works (fruits, manifestations or evidences -- the works/fruits including those qualities mentioned above in 2 Corinthians 7:9-11).
Acts 26:18
...to open their eyes [conviction of the Holy Spirit at hearing the Truth], in order to turn them from darkness to light, and from the power of Satan to God [Matthew 6:24], that they may receive forgiveness of sins and an inheritance among those who are sanctified by faith in Me.
Acts 26:20 
but declared first to those in Damascus and in Jerusalem, and throughout all the region of Judea, and then to the Gentiles, that they should repent, turn to God, and do works befitting repentance.
Since we are not saved by works of the Mosaic Ceremonial Law, I believe the "first works" mentioned in the following text is that "clearing of wrongdoing" (as outlined above). Here Christ, while watching believers and seeing them starting to fall away, is calling the apostatizing Church of Ephesus back to repentance, unless He remove their Lampstand: 

Revelation 2:4-5
Nevertheless I have this against you, that you have left your first love. Remember therefore from where you have fallen; repent and do the first works, or else I will come to you quickly and remove your lampstand from its place—unless you repent. 

And there are "Fruits of Repentance" which also, I am thinking, must be these same "works" of repentance... 

Matthew 3:8
Therefore bear fruits worthy of repentance. 

This all lines up with Isaiah's declaration of repentance:
Isaiah 1:16-20 "Wash yourselves, make yourselves clean; Put away the evil of your doings from before My eyes. Cease to do evil, learn to do good; Seek justice, Rebuke the oppressor; Defend the fatherless, Plead for the widow. "Come now, and let us reason together," Says the LORD, "Though your sins are like scarlet, They shall be as white as snow; Though they are red like crimson, They shall be as wool. If you are willing and obedient, you shall eat the good of the land; But if you refuse and rebel, You shall be devoured by the sword"; For the mouth of the LORD has spoken.

Isaiah 55:7
Let the wicked forsake his way, And the unrighteous man his thoughts; Let him return to the LORD, And [then] He will have mercy on him; And to our God, For He will abundantly pardon.
And James'

James 1:21
Therefore lay aside all filthiness and overflow of wickedness, and [then] receive with meekness the implanted word, which is able to save your souls. 

And Jeremiah's:

Jeremiah 26:13
Now therefore, amend your ways and your doings [the clearing], and obey the voice of the LORD your God; THEN the LORD will relent concerning the doom that He has pronounced against you.

And Ezekiel's:

Ezekiel 18:27-32
Again, when a wicked man turns away from the wickedness which he committed, and does what is lawful and right, he preserves himself alive. Because he considers and turns away from all the transgressions which he committed, he shall surely live; he shall not die. Yet the house of Israel says, ‘The way of the Lord is not fair.’ O house of Israel, is it not My ways which are fair, and your ways which are not fair? “Therefore I will judge you, O house of Israel, every one according to his ways,” says the Lord GOD. “Repent, and turn from all your transgressions, so that iniquity will not be your ruin. Cast away from you all the transgressions which you have committed, and get yourselves a new heart and a new spirit. For why should you die, O house of Israel? For I have no pleasure in the death of one who dies,” says the Lord GOD. “Therefore turn and live!” 

And Jonah's preaching to Nineveh: 

Jonah 3:8-10
But let man and beast be covered with sackcloth, and cry mightily to God; yes, let every one turn from his evil way and from the violence that is in his hands. Who can tell if God will turn and relent, and turn away from His fierce anger, so that we may not perish? Then God saw their works [of repentance; their "clearing"], that they turned from their evil way; and [then] God relented from the disaster that He had said He would bring upon them, and He did not do it. 

Christ even referred to this repentance of Nineveh. How much more severe will the punishment be those that refuse to repent at His calling?
Matthew 12:41
The men of Nineveh will rise up in the judgment with this generation and condemn it, because they repented at the preaching of Jonah [before they were granted mercy]; and indeed a greater than Jonah is here. 

Confessing [realizing, admitting] AND forsaking sins are steps needed to attain God's mercy: 

Proverbs 28:13
He who covers his sins will not prosper, But whoever confesses and forsakes [stops them] will have mercy. 
And I believe this process could be looked at as "preparing the way of the Lord, Making His paths straight (in our heart). And "breakign up the fallow ground of our heart"...
Luke 3:4
as it is written in the book of the words of Isaiah the prophet, saying:“ The voice of one crying in the wilderness:‘ Prepare the way of the LORD; Make His paths straight.

Jeremiah 4:3
For thus says the LORD to the men of Judah and Jerusalem: “ Break up your fallow ground, And do not sow among thorns (Mark 4:18). (see context in Jeremiah 4:1-4).

Hosea 10:12
Sow for yourselves righteousness; Reap in mercy; Break up your fallow ground, For it is time to seek the LORD, Till He comes and rains righteousness on you.
There are many, many more examples of this type of dramatically life changing repentance and stopping of sin  in the Scriptures. And if this is all true, and I believe it is, then the majority (all?) of the Churches today are (supposedly) leading people to Christ by means of "worldly sorrow" (which leads to death), and thus true repentance is not taking place and there is therefore no contact with the Blood of Christ or the resulting salvation. I totally believe that today we have millions of false converts in the Churches (and has been for hundreds of years) because of the false teachings concerning the nature of what sin and repentance is.

Repentance is a clearing of wrongdoing, a time of refreshing, and a true change of heart that is to take place BEFORE remission of past sins (2 Peter 1:9; Romans 3:25) where initial salvation is granted (Titus 3:7; Romans 8:24). I also believe that if someone were to truly experience this godly sorrow and repentance by means of reading the Bible on their own, if they then go into the Churches they will be put to sleep by the false grace message they will hear, the fluff that tickles their ears (2 Timothy 4:2-4) which keeps them coming back (1 Timothy 6:5-6), and all the doctrines of men and demons (1 Timothy 4:1-2) which has nothing to do with turning people from their sins (Mark 4:12; James 5:20). Anything other than the true message of biblical repentance is another gospel (2 Corinthians 11:3-4).
Far and wide they teach that grace is unconditional favor in spite of sin (saved in your sins; "come as you are; nobody's perfect") and that grace is God's willingness to overlook our continual sin, but true grace is really found through true repentance. To be noted also is the fact that we can receive God's grace in vain (2 Corinthians 6:1) and we can also believe in vain (1 Corinthians 15:2).

Look at what many are not taught the Bible says of God's grace:
Titus 2:11-12
For the grace of God that brings salvation has appeared to all men, teaching us that, denying ungodliness and worldly lusts, we should live soberly, righteously, and godly in the present age...

Hebrews 12:28
Therefore, since we are receiving a kingdom which cannot be shaken, let us have grace, by which we may serve God acceptably with reverence and godly fear.

If someone truly experiences God's grace and His offer for mercy and life, and thus feels a love for Him, they will be taught to "deny ungodliness and worldly lusts" and to "live soberly, righteously and godly" and "serve God acceptably with reverence and godly fear" "in this present age", (and not in some glorified state in eternity). This begins in the process of repentance, where we initially deny ungodliness and worldly lusts and are cleared as a result of our obeying the truth (1 Peter 1:22). If someone does not experience this type of Biblical Repentance, they will not be able to come into contact with Christ's blood for the remission of sins, and will remain subject to the second death. This is a sobering truth that many do not realize. We cannot be, as modern Christianity teaches, be "saved in our sins". Christ came to save us FROM our sins (Matthew 1:21)! We must reject the doctrines of men and listen only to the Word of God!
"These people draw near to Me with their mouth And honor Me with their lips But their heart is far from Me And in vain they worship Me Teaching as doctrines the commandments of men" Matthew 15:8-9
Who is it that regenerates our heart and influences (not compels) us to live for God?  The Holy Spirit...  Yet the Bible says that we cannot even receive the gift of the Holy Spirit, thus none of His workings, unless we first obey Christ (by means of Biblical Repentance and loving and following Him):
"And we are His witnesses to these things, and so also is the Holy Spirit whom God has given to those who obey Him.” --Acts 5:32 

“If you love Me, keep My commandments [repent, believe, love]. And [then] I will pray the Father, and He will give you another Helper, that He may abide with you forever" --John 14:15-16

Not only do I not find in the Bible that man is depraved from birth, but I find that repentance means more than a willingness to stop sinning... it means we actually need to stop sinning (wilfully disobeying God) in order to be saved; we need to forsake wickedness, in response to our conscience (influenced by God's Word and Spirit) and by the power of our will that the Lord has equipped us with when He formed us in our mother's womb.
Either men's doctrines that say we can't obey God and we are born wicked (which hinge on a few "proof texts") are in error, or the entire Bible is. The Scriptures clearly demonstrate that man has the ability to forsake wickedness, and that he MUST do so before he will be granted mercy from the Lord and be granted the remission of sins.

Deuteronomy 30:19
I call heaven and earth as witnesses today against you, that I have set before you life and death, blessing and cursing; therefore choose life, that both you and your descendants may live;

We have a free will and can choose life or death, sin or righteousness.... we can obey or disobey, live eternally or be damned for eternity: 

Romans 6:16
Do you not know that to whom you present yourselves slaves to obey, you are that one’s slaves whom you obey, whether of sin leading to death, or of obedience leading to righteousness?

1 John 3:7
Little children, let no one deceive you. He who practices righteousness [works from the heart - Galatians 5:6] is righteous, just as He is righteous.

Sin is a choice, not a nature born into us, or imputed to our account or soul.

James 1:14-15
But each one is tempted when he is drawn away by his own desires and enticed. Then, when desire has conceived, it gives birth to sin; and sin, when it is full-grown, brings forth death. 

Temptation is not sin; Jesus was tempted IN ALL points as we are:

Hebrews 4:14-15
Seeing then that we have a great High Priest who has passed through the heavens, Jesus the Son of God, let us hold fast our confession. For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin.

There is no sin that someone cannot overcome; people quit addictions every day, even without God. What I am tryign to say here is that we have a choice to sin or not to sin; it's up to us and there is nothing in us or outside of us that forces us to sin; it is born of desire and when united with the will it produces sin, which brings forth moral death and eventually eternal death. Sin is only in our nature as far as we allow it to be as a practiced and enjoyed habit; it is as if it were a welcome guest BUT we can always kick it out.

The question here is not if there has ever been a sinless person, but rather if it is possible that a man live sinless? And yes, I believe it is possible. Has any man other than Christ ever been sinless or will any other than Him ever be sinless? Most likely not, but that doesn't mean it isn't possible. Why "throw out the baby with the bathwater"? If we go around saying we are born sinners and can never be free of sin, why would anyone ever try? On this point, take a look around the churches, not many people are even trying!! To most, going to church is a social experience and has nothing to do with God. They all think they are "saved in their sins" and continue to live in a worldly fashion... they, just like the rest of the world around them, are mostly interested in sports, music, video games, luxury, status, sex, food, entertainment, movies, TV, money, cars, philosophy, news, gossip, nature, politics, education, technology, fashion, health, etc. They are most often more interested in these vain amusements and fleshly lusts than they are in digging for truth or of loving and obeying God! This is nothing less than idolatry! Modern Christianity has barely a trace left in common with the early (first 3 centuries) of the Church! I mean, yeah, it sounds good to say that if we love God we will not want to sin; But the truth is that if we truly love God we will not find it in us to be able to sin!

1 John 3:8-9
He who sins is of the devil, for the devil has sinned from the beginning. For this purpose the Son of God was manifested, that He might destroy the works of the devil. Whoever has been born of God does not sin, for His seed remains in him; and he cannot sin, because he has been born of God.

John 14:21
He who has [knows, hears] My commandments and keeps them [James 1:22], it is he who loves Me. And he who loves Me will be loved by My Father, and [then] I will love him and manifest Myself to him.”

1 John 2:3-5
Now by this we know that we know Him, if we keep [obey] His commandments. He who says, “I know Him,” and does not keep His commandments, is a liar, and the truth is not in him. But whoever keeps His word, truly the love of God is perfected in him. By this we know that we are in Him.

Love is obedience, and obedience is doing what is right, and doing is right leaves NO room for sin, and NEVER excuses or defends it. 

Luke 14:27-28
"And whoever does not bear his cross (die to self) and come after (follow my example and obey) Me cannot be My disciple (or be saved). For which of you, intending to build a tower, does not sit down first and count the cost, whether he has enough to finish it" —The Lord Jesus