This book is by Elaine Pagels.
Before reading this book, I had understood that the current "mainstream" understanding of Satan is different from that of most pre-Christian Jews, but I was not sure how we got to this point. I was not expecting what this book proposes as the explanation, but it does sound reasonable.
According to Ms. Pagels, the idea of Satan as waging a battle against God has a lot to do with the situations the Jews faced during the times not long before the destruction of the Temple and the subsequent sectarian fighting that led to the separation of the Jews and the Christians. This continued to develop with the persecution of the Christians by the Romans and later during the campaign of the orthodox Christians against heretics in the early church and beyond. Demonizing an opponent is a simplified way of putting it.
One side benefit to me is a new perspective on the Gospel of Thomas and even more so on Valentinus and the Gospel of Phillip. I had written off the latter two as too way out, but Ms. Pagels' explanation of them makes me want to take another look. I will start with some of her other books on these subjects.
The Satan book did get a little dry in the middle at times, but it was mostly a good read. Give it a try and see what you think.