This portion starts a new chapter in the history of the Jews. Many unfortunate things have happened in the first 2,000 years since the creation of the world: Adam and Eve are exiled from Eden, Cain kills Abel and a flood destroys the world. Now,God decides to begin again. Abraham and Sarah are the couple he chooses to help bring forth Godly spirit into the world. This time God will succeed.
It is often hard to work on a project, only to realize that it has gone in an entirely wrong direction — a drawing, a homework essay. Sometime, we try to work out the kinks and that makes it even worse. Although it is hard to give up on a work in progress, sometimes it is easier to throw the whole thing out and begin again. And if God did it, you can, too!