Why did God choose Abraham to be his earliest ambassador after the flood and the Tower of Babel?

Answer 1

I think that God chooses people to fulfill major roles at particular times but then puts them through a period of testing. In the case of Abraham, he was certainly a flawed character. But his greatest test was when he was willing to allow his son to be sacrificed in obedience to God. There are other cases when God chose certain people who ultimately failed, e.g. Saul and Solomon.