Where does the concept of sin come from?

"when u tell that god wants to erase our past... do u mean that he will forgive us for all the sins that we have committed..i dont agree with this. I think whatever you do in this life , on this earth, ur karmas will be that and you will have to pay for ur deeds gud or bad .. here on this earth and in this life itself.There is one more concept in this post that i have heard a lot of time. That we are sinners. why do u think that way? I think when god gave us the birth of human beings, someone who is intelligent and who can think.. he has blessed us and haS given us the oppurtunity to do the right things and make this world a better place. Where does this concept of sin come then?"
These are really good questions! And I'm glad that Raven has asked them.
Yes Raven, when I say that God wants to erase our past I mean the sin that we as human being have committed. God is a holy and just God who loves us and wants to have a relationship with us. He gave us His 10 Commandments (Deuteronomy 5) for our benefit as a loving parent gives us boundaries for our well being. We of course don't obey and break that relationship. So God in His goodness provided a way to restore us to Himself (I'll get back to that in a minute.) We first need to admit we have broken God's law by: lying (you'd be lying if you said you never ever lied), stealing something (even from your Mom's purse), disobeyed our parents, and committed adultery (with our mind, actions, and sex outside of marriage.) Or whatever law we've broken. God has given us intelligence and the opportunity to do what is right. But we like our way better and refuse His love (sometimes subconsciously sometimes not). God designed us in His image (Genesis 1:26). He did not design animals in His image, we are His favorite! He wants to adopt us if we will repent(be sorry and turn away from our sins) of our disobedience. God has everything we need. But we refuse His help.
Back to God providing a way for us. Romans 5:8 But God demonstrated His own love towards us in while we were yet sinners Christ died for us. Jesus paid the price to restore us to the Father, not because we are so good and perfect but because He loves us and wants us with Him always! We can accept or reject God. The Bible says one day we will give an account for what we did with the free gift of Jesus. You are either for God or against Him (no in between). He wants to forgive us but we need to be wilingl to humbly ask for help. Our pride at times does get the best of us..... I know I've been there.