explain the quote "There is only one sin, only one. And that is theft" from baba

Baba actually says,

Now, no matter what the mullah teaches, there is only one sin, only one. And that is theft. Every other sin is a variation of theft. Do you understand that?"

Amir feels nothing but shame and self-loathing over Hassan's rape. How does Amir tell Babba, a man who once wrestled a bear, that he let Hassan's innocence be stolen by Assef?

It's pretty simple, I can't remember if the full quote is in the movie or the book I've been through both so many times. It goes something like this,

 There is only one sin, only one. And that is theft. (Here comes the explanation) Every other sin is a variation of theft... When you kill a man, you steal a life.You steal his wife's right to a husband, rob his children of a father. When you tell a lie, you steal someone's right to the truth. When you cheat, you steal the right to fairness. There is no act more wretched than stealing.

I know this post is old, but possibly someone else needed the answer. :-)