one thing the series implies...but does not necessarily state...is the origins of the divide between jews and muslims. Abraham, who is considered the founder of the Israeli nation...is tested by god repeatedly to test his faith. he and his wife cannot have children. his wife suggests he "lay" with a handmaiden. he does. and a child is born. Ishmael. a child he loves. but his wife can't stand to see Abraham fathering a bastard child...even if it was done at her suggestion and had her consent. god then tells Abraham's wife that she will have a baby. she will name it isaak. when this second, but legitimate child is born, his wife continues to be unhappy Abraham has a first, illegitimate child. he casts his handmaiden and his first bastard child out into the desert, with promises from god that they will be taken care of.
I think both Ishmael and issac both have claim to being Abraham's true son. and the two sides have not gotten along since.
I think.