In the Book of Genesis Abraham is promised by God that he will father many nations. Many things from the earliest literature is debatable but this promise has come true in spades. Jews, Christians and Muslims claim the old man of Mamre as their father.
As is often the case there is a lot of sibling rivalry going on and the descendants fight over the will and the dividing of the patrimony. There are emotional cut-offs which prevent healing of wounds. Such is our lot and yet we have quite a lot in common.
In Abraham we have a hopeful ancestor who would better for us than we have chosen for ourselves.