It seems abundantly clear that there needs to be clarification as to what repentance is, and is not, and what our contention is with certain misunderstandings of what repentance is.
My contention is that repentance does not mean 'stop sinning'. By saying that, I do not mean that repentance has nothing at all to do with sin... of course it does. The Greek word for repentance is metaneo which means to change one's mind. A Biblical definition would be to feel true remorse over one's sins. This certainly includes the will not to sin again. However, the will to not want to sin again does not necessarily equal not sinning again. I certainly do not want to sin again, but will I probably sin in the future? Yes. Am I thus impenitent? No. My response to future sins also reveals my repentant heart.
There are many things in view to be repented of when Jesus declared, "Repent and believe the Gospel!" He was speaking to Pharisees, commoners and crooks. I think the Scripture makes it pretty clear what sins made Christ more angry: self-righteousness more than fornication; justifying oneself before God more than tax-fraud, etc. Repentance therefore is not just addressing outward sins, but inward sins. In fact, telling a person to give up their outward sins is really only attacking the symptoms and not the real problem. The real problem is the heart, from where all outward actions flow (Matthew 15:19). Repenting from outward sins is totally useless if the heart is not dealt with. It is for this reason that I believe Jesus meant something much deeper than "stop your outward sins" when He declared, "Repent and believe the Gospel". That would be very shallow indeed. And when Paul preached that "God commands all men everywhere to repent", he meant much more than just 'cut down all your idols, boys'. The Athenians could take an ax to every statue on the Grecian Peninsula and still would have not truly repented. The repentance that God is looking for is "rend your heart, and not your garments".
The greatest sins of all are pride, mercilessness and self-righteousness. I really don't believe Jesus came preaching "stop your beer guzzling and your dope smoking!" All those will fall away when the heart of the matter is taken care of. "Repent" therefore means to humble oneself before the mighty hand of God, to acknowledge one's sinfulness in light of the "glorious holiness" of God, to beat one's breast in remorse and plead, "God be merciful to me a sinner." That is true repentance. I don't think God can show mercy on the man who stops all his outward sins and then tells God, "Okay, I'm good. Forgive me now". Such a man has never truly repented.
Jesus came to the most religious society this world has ever produced. They preached abstinence and piety better than any other monastic system could ever have... but Christ came in to demolish human pride and confidence in outward piety. Christ preached repentance of the heart, so that an adulterous woman weeping at his feet was more righteous than the morally blameless men who invited Jesus over for dinner.
Paul declared, "as touching the righteousness that is in the law, I was blameless." Outwardly I was spectacular! But when Paul met Jesus and was thrown to the earth, the light of truth exposing his inward sinfulness, Paul soon found out that all of his righteousness was in fact worth "dung", and he didn't just need forgiveness of past sins... what he needed was an entire inward transformation. The apostle of the faith, born again of the Spirit of God, could now proclaim the everlasting Gospel by the revelation of Jesus Christ given to him: "Christ Jesus came into the world to save sinners; of whom I am chief."