What I find interesting is that the idea of atonement has not been elaborated on untill quite late in the gospels for example: Matth 20 (ca 45 AD)and barely a few lines are devoted to that. The only real difference there is the gospel of John but then again that one comes at least 30 - 60 years after Jesus. Quite some time to develop some fancy religious idea. And that brings us to Pauline letters.
Cheers
Borgia