Can our good deeds change the effect of our bad deeds?

I don't think we can compare good and bad deeds with revenue and expenses. Expenses are a necessity of business, they can be reduced but never eliminated. Bad deeds are not a necessity, and they do damage. Sometimes we can try to un-do a bad deed by making amends, but damage was done. Also, what if someone did lots of good deeds, but committed one horrible crime? I think you're on the right track though, we should always try to do as much good as possible.

No good deed can change the effects of a bad deed, nor is the converse true. They are what they are. No one can know the many repercussions of any act we do, but we can strive to do "the right thing." As conscientious humans, we have a strong compunction when we err and an equally strong need to repent and reverse this error. This is not a bad thing in itself, for many good things have been borne from a single error in judgment, but the initial error is still there. To paraphrase Martin Buber, "it's better not to rake the muck this way and that. Just start now and do good." "Truth is no harlot who throws her arms around the neck of him who does not desire her. To the contrary, she is so coy a beauty, that the man who sacrifices everything to her is still not assured of her favors." -Schopenhauer

This is kind of like Karma, or what goes around comes around. Good deeds can offset bad deeds, but the bad deeds don't go away. You are always responsible for your actions and your bad actions don't go away and can't be erased but you should always try to balance the books

C.S. Lewis said that life is made up of decisions and that every choice we make turns us into a person who is either a little more like a demon or a little more like Jesus. It has been said that it is never too late for a Christian to do the right thing and I would imagine that this precept probably carries over in a general way to most everyone else too. However, from a salvation stand point, a larger balance of good deeds as opposed to bad deeds doesn't work, just like if you showed up in a court room and told the judge that all of your life you had been a law abiding citizen you just made a mistake this one time. The judge might commend you for your good life but he has to uphold the law and he has no choice but to find you guilty for the law that you did break. It's the same way when a person comes before God for judgment. He has already said that if a person breaks even one of his laws they deserve to go to hell and once having said that he can't just let someone off the hook because that would make Him a liar or a corrupt judge. That's why I'm so glad that God loved me enough to send Jesus to pay my sin debt for me because on my own I would have been found "guilty" a long, long time ago. Romans 6:23 For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.

I think it is a lot more like you suggest. There is a balance between the good and bad deeds. The Christians are right about part of it, in that what is done cannot be undone. Still, I think it can be taken into account in your overall karmic load. I think it's kind of lazy and dishonest to push off all your sins off on Jesus (who is probably not alive right now) and expect him to solve it all for you. I'm not saying Christians are dishonest, because many of them really believe this. I just don't think it was God's teaching. Somehow it got bungled up in the translation. If you extend this logic it leads to the following conclusion: You can sin, then truly repent and accept Jesus as your Savior, then it's OK to go ahead and sin again as much as you like, because you're already saved. Well, I don't believe it works that way. Another problem I have with some of the ranting supposedly Christian people are putting out (not on this question though) is that they are saying if you don't do this or that, you're going to go to Hell, etc. Isn't it up to God to decide who goes to Heaven and Hell? I think there are many paths to God. Each person has his or her own unique path, though we share a lot along the way. I don't think all sins are equal. That would be stupid, putting telling a little "white lie" on the same level with murder. I think your math analogy holds, whether you believe in reincarnation or not.

We can't reverse the effects of our 'bad deeds' (sins), be they intentional or otherwise. As it is often said, "what is done cannot be undone." Therefore no amount of good deeds we do can make up for our sins. However, our sins are forgiven when we genuinely accept Jesus as our Saviour. Only the blood of Jesus (which was shed on the cross) can cleanse us from sin because only He is perfect (without sin). No one is perfect, except God. Thus we will inevitably make mistakes or sin. The important thing is to repent and try not to commit the same sin/mistake again. And by the same analogy as that we do not have to be clean before we take a shower, we do not have to be sin-free before we can receive salvation. It is never too late to receive salvation.