Note the bible on this issue:
The World: Bogus Belief #29
I'm basically a good person.
There is none righteous, not even one; there is none who understands, there is none who seeks for God; all have turned aside, together they have become useless; there is none who does good, there is not even one. (Rom 3:10-12) NAS
Having spoken to a few on the merits of becoming a Christian, I get this answer sometimes. The cause is three-fold:

1. They don't recognize God's holy nature (He can't tolerate ANY sin).
2. They use themselves as the standard of righteousness.
3. They don't know or don't believe the bible when it says stuff like this.

If you could get to heaven on your own steam, then God wasted a whole lot of time being tortured and killed for your sake. Where were you when God was designing the plan of salvation? He should have asked for your advice on what it took to be a "good" person, acceptable to live in His presence!

Of course, many are doing just that. Each has their own standard of righteousness. The old bromide, "don't smoke, drink or swear" was once widely popular. In the last decade, the standards have been relaxed a bit. Now, God won't care if you stick with low tar-and-nicotine cigarettes. As long as you're not a gutter bum, drunkenness is winked at. You should curse intelligently, not spuriously.

All are saying the same thing: "I don't need the blood of Christ. I'm good enough on my own. Maybe I sin now and then, but I've done a lot of good in my life too. That should count for something." They actually believe God will weigh the Good against the Bad. Guess what? He won't. If you're found without Christ, you will lose your soul for all eternity.
How then can we be saved? All of us have become like one who is unclean, and all our righteous acts are like filthy rags. (Isa 64:5, 6) NIV
When a person "puts on Christ" (Gal 3:27) God "sees" Jesus, not you. In fact, His intent is to make you into a "copy" of His Son; being "conformed to His image." (Romans 8:29) This doesn't mean we become some mindless clone, but that our hearts are being changed...we are being changed from the inside out. Our hearts change and our actions and words reflect that.

God doesn't care about whether you smoke 1 cigarette or a pack a-day. He didn't lay down guidelines to micro-manage your life. In fact, one of the reasons the Law was given was to prove that man's heart was essentially turned against God. We are law-breakers by nature.
But now a righteousness from God, apart from law, has been made known, to which the Law and the Prophets testify. This righteousness from God comes through faith in Jesus Christ to all who believe. There is no difference, for all have sinned and fall short of the glory of God, and are justified freely by his grace through the redemption that came by Christ Jesus. God presented him as a sacrifice of atonement, through faith in his blood. He did this to demonstrate his justice, because in his forbearance he had left the sins committed beforehand unpunished— he did it to demonstrate his justice at the present time, so as to be just and the one who justifies those who have faith in Jesus. Where, then, is boasting? It is excluded. On what principle? On that of observing the law? No, but on that of faith. For we maintain that a man is justified by faith apart from observing the law. (Rom 3:21-28) NIV
There you have it. Christ is our righteousness. He did it at the cross. The debt was paid that you can't pay. It's a slap in God's face if you think you can come up with your own salvation instead of accepting the one He has already freely provided.